New MSD Distributor

[Nuts]

Okay, I received my new MSD Distributor with vacuum advance, that was the easy part... Just had to pay $$$$ and there it was... :clap I hope that most of you are out enjoying a good Show-n-Shine somewhere, but also hope that someone can help me out !!!! :clap

The specs:

I only have about 4-5 in. of vacuum at 800 rpm idle ? The advance on the distributor requires 15 in. to function. The vacuum goes up to 16-20 in. at 2500 rpm. With the advance disconnected I get 12 degrees advance at idle and 23 degrees of advance at 2500 rpm. I also get some dieseling at shut off... With the vacuum hooked up I get the same 12 degree at idle and 38 degrees at 2500 rpm and no dieseling at shut down. I have the vacuum line plugged into the right hand port, rear carb of the Edlelbrook 500 cfm carbs

The question:

Is the vacuum at idle to low ? What should it be ?

Am I plugged into the correct port on the carb ?

Should I be getting some vacuum advance to idle ??

Is the total advance 38* at 2500 about right ?

Oh BTW the motor seems to be running good with the new distributor !!!! :) :clap

[ROYALOAK62]

Nuts,
Just checked my set-up. My vacuum line from the distributor goes to the rear drivers side vacuum pick-up on my dual Edlelbock 500's. With all the others caped. When I installed my Edlelbocks & MSD at the same time I had to reajust the cabs & the timing over and over again for the best vacuum.

Dave

[fatride]

First, post your cam specs. Second, you must have a wild cam or something is amiss ! I have seen some pretty wild cams that would make 10" of vacuum at idle. You can get an adjustable vacuum advance unit that will pull advance at a lower than stock vacuum. If your 500 cfm carb is the same as the 600 you have the vacuum pot hooked to manifold vacuum. My cam is a solid roller with 230/240 @ .050. I have 12" to 13" at 800/900 rpm. You can change the advance bushing to the black one in the MSD dist. and have 20 dgs initial and 36 total and it should be all in by 2500/2800 with an auto tranny. In this case you can hook the vacuum line from the vacuum pot to a timed port on the carb as you do not need added advance at idle. I would not run with any more than 50 dgs advance at light throttle cruise. It sounds like to me that you need more initial timing, this will allow you to back off the curb idle screw and get the carb into the idle circut. Try it!

[Skip FIx]

I agree unless you have a giant cam you should have more vacuum than that. Although my Pontiac motor drops from 12" at 900 to 8" @ 900 in gear. Many of the factory vacuum canisters were full in by 10". I would assume MSD would figure their distributors were going into hot rods with less than factory vacuum.

[jim_ss409]

Like Fatride said, if you've got a big cam you need a lot of initial advance. I think the reason for this is that a big cam has overlap which causes exhaust gasses to get sucked into the intake by the vacuum from the other cilinders. So at an idle you're trying to burn a mixture of air and fuel that's somewhat contaminated by exhaust gasses. I think it takes a bit longer to burn the contaminated mixture so advancing the timing seems to help. More advance also helps the car run cooler.:deal
I think there's two reasons that a car with retarded timing runs hotter... First, the main part of the combustion happens when the piston is part way down the bore. This would expose the cylinder walls, and cooling system to more heat. And the other problem with retarded timing is that the fuel-air often doesn't finish burning untill it's on it's way out the exhaust manifolds. So once again there's more heat in the exhaust ports of the heads. That has to be absorbed by the cooling system. And the heat from the hot manifolds just contibutes to higher underhood temperatures.
Proper timing also improves you vacuum readings and alows you to lean out the fuel mixture. This in turn means that less fuel is being consumed at an idle and it also meas there's less heat for the cooling system to absorb.
I'm no expert and these are just my opinions but I think that getting the timing right is very important on a high performance engine.
I think the ideal setup is to use an adjustable vacuum pot (Crane Cams makes one) But it's a bit of work to get one working just right. If I remember correctly they come with more travel than you might want and you've got to use epoxy, or weld, or whatever to reduce the total travel. But if you just do what Fatride suggests,,, 20 deg. initial with about 15 or 16 degrees mechanical for a total of 35 or 36 degrees it should run well. As he said you should also put in lighter springs so that it's at full advance by about 2,800. Then, with the vacuum advance connected you'll have a total of about 50 degrees or so. That sounds like a lot, and it is but remember that the vacuum advance only works at part throttle. At full throttle there's very little vacuum so the vacuum advance doesn't work. By the way, 20 degrees initial is a lot. It should be fine though. But if you try to run more than that it might get hard to crank over, especially on a hot day.
Good Luck!:beerbang

[jim_ss409]

Skip Fix, I guess I was typing at the same time as you were.:deal
As you said you'd think that MSD would have used a vacuum pot that didn't take soo much vacuum to operate. But they didn't. I think Nuts is right and it takes about 15" I've got a GM muscle car pot back at the shop that's fully open at about 10 deg.:scratch and the Crane ones require even less when they're set to the softest setting. The MSD distributor also comes with a very conservative advance curve. It makes you wonder if they have there customers in mind when they build this stuff.:dunno

[Nuts]

Okay, here are the specs from the cam. I wasn't sure what you might want so I loaded a pricture of the spec sheet. The cam is not really big and I'm running hydrolic lifters.

http://community.webshots.com/photo/106281129/2420325930046005004Rktwwk

Looks like all I got was the dreaded "Red X" here is a link: http://community.webshots.com/photo/106281129/2420325930046005004Rktwwk

One question that comes to mind after reading all the posts is - Am I using the correct carb port for vacuum ??? :dunno And am I checking the vacuum at the correct port ??? :dunno

The MSD comes set up at a 10* timing curve put can be adjusted with different springs. The total advance can also be adjusted by using a different stop.

Any more questions please feel free to ask away...

[Nuts]

All, Thanks for you assistance - Here is an update...

I checked the vacuum using the manifold port. I've got 12 - 15 in of vacuum on that port. I pulled the advance into that port and the idle just settled down. Ran so smooth I thought something went wrong. It also jumped from 800 rpm to 1100 rpm, so I adjusted the idle screw to bring it down. I left the initial advance at 12 degrees and now have 23 degrees advance at 800 rpm idle. I took her out for a drive in traffic today and never got over 190, even at the many lights I hit during the drive. It was about 80* out when I went. Overall she is quite a bit quieter also... That's the GOOD news.... :clap :) :cheers

Now the BAD news.... I have a hesitation moving from idle to speed. It settles right out after the rpms come up and runs good as long as you don't punch it real hard. I did not mess with the adjustments on the carb and I'm just not a good enough mechanic to know if it's flooding or starving...:dunno :dunno

[rwagon57]

Nuts,

Look at the trouble shooting section in the Edelbrock manual. My 1st guess is your accelerator pump shot is probably too small. The Edelbrock tuning guide is really very helpful.

[jim_ss409]

The hesitation problem could also be at least partualy timing related. The problem might be that you've got just enough vacuum at an idle to opperate the vacuum advance mechanism, but, when you crack the throttle the vacuum drops and so does the timing. If you go with a more agresssive setting on your initial and mechanical timing you may be able to put the vacuum hose back to the non manifold port and still have a nice running engine because you'll have plenty of advance even without the vacuum. (see Fatrides post) If you put in the black advance stop bushing and put in the two light blue springs you'll reach full advance by about 2600rpm (you want about 34-36 degrees total with the vacuum advance temporarily disconected and blocked) This setup SHOULD give you about 20degrees at an idle, again with the vacuum advance disconected. But it's hard to say for sure because the soft springs will already be starting to advance the timing. This setting is fairly quick and so you might want to listen for signs of pinging the first time you take it out.
If you want to try something quicker and easier that will almost certainly help just pop off the cap and rotor and exchange the heavy silver springs for the lighter blue ones. That way you should be able to leave the timing and the vacuum hose where it is. It's probably won't work as effectivly as the other setup but it's worth a try.:dunno By the way I got the number for a vacuum pot that opens with about 8 to 10 inches of vacuum and gives about 15degs of advance. It's made by Standard Automotive Parts and the number is VC-177 I just thought I'd add that in case somebody was looking for one.

[desapience]

MSD has one of the finest out-of-the-box distributors made, and comes with a tech manual that is simple to understand and follow! READ IT THROROUGHLY!

The reason MSD distributor (part #8393) comes out of the box with a "conservative" advance curve (2 heavy silver springs) , is to make certain the buyer starts out with a safe-setting point from detonation, and not because MSD engineers are cluless about what applications their distributors will go into. They are protecting ALL buyers, right off.

For my 409/446 stroker, with 2-600 cfm Edelbrock 1404's, and 11:1 compression, with a hydraulic Z-11 cam, this is how it's set up, beginning with the carb jetting.

Take the .095" secondaries that come with the carbs out of the box, and place them in the primaries. Buy 2 sets of .086" jets and place them in the secondaries (discard the original primary jets; you won't need them).

Install the MSD vacuum hose to the rear carb's timed vacuum port. Set your basic timing to 12 degrees.

At this point, you'll still have the two heavy silver springs in the distributor (as it comes out of the box). Run the engine..., take it up on the road, and listen carefully for detonation (pinging), and note your operating temperature.

IF you have ANY pinging at all at this point, you're screwed... you'll need higher octane gas. But, the odds of that happening with the advance curve from the 2 heavy silver springs is pretty much nill.

Now you can play a bit with mixing up the added springs MSD provides. I did, and first went to the two light blues... there was a very notable increase in power, but, had some small rpm ranges in high gear (700R4) that brought out some light pinging (on straight 93 octane). So, I went to mixing one light silver spring with one heavy silver spring, and, the pinging disappeared entirely, and still had a very significant increase in power over the out-of-the-box set-up.

I did NOT change the advance stop bushing... the mechanical advance provides 21 degrees advance -- so, 12 + 21 = 33 overall. If you really want 34, change to the appropriate bushing, or set the initial crank timing to 13.

I might also mention that a very slight surging when cold, that also existed with the out-of-the-box setup, went away, entirely... even with the out-of the box jetting rods and staging spirings on the 1404's.

Going from the MSD 2-heavy silvers to a mix of one light and one heavy silver, you should also note a small decrease in operating temperature.. a quicker advance curve makes the engine run a bit cooler.

Also, I've started using an octane booster. In the past, I've experienced some variances in gasoline quality going from one gas station to another.. the booster adds insurance from any light pinging coming from lesser quality gas sneaking its way into my tank.

Hope this helps

Denis (Dr D)

[Ronnie Russell]

Denis, 1404s???? Thought they were 500 cfm.

[mac1]

Denis, I also have an MSD out of the box distributor. The instructions do say to hook up to a timed vacuum port. I always heard the timed port was for pollution controlled vehicles, and you should hook it up to a non timed port, (small block vehicles anyway) for better performance. Would you mind telling us why the timed port??? Thanks Mac

[JimKwiatkowski]

By the way I got the number for a vacuum pot that opens with about 8 to 10 inches of vacuum and gives about 15degs of advance. It's made by Standard Automotive Parts and the number is VC-177 I just thought I'd add that in case somebody was looking for one.

Jim Thanks for the part #,since I have the cooling system running cool in the 57,its time to see if I can get the vacuume advance to work on my MSD :dunno

[desapience]

Denis, 1404s???? Thought they were 500 cfm.

Hey Ronnie,

You're correct, I meant to type 1405's... thanks for catching my error!

Denis

[desapience]

Denis, I also have an MSD out of the box distributor. The instructions do say to hook up to a timed vacuum port. I always heard the timed port was for pollution controlled vehicles, and you should hook it up to a non timed port, (small block vehicles anyway) for better performance. Would you mind telling us why the timed port??? Thanks Mac

Mac,

Even given the instructions that came with the MSD, I also tried going to the non-timed port, and here's the problem I found.

Remember, I did first change to the two light blue springs in the mechanical advance, which shifted the advance curve pretty significantly, and gave a very noticable increase in power, but, with it came some pinging when the engine was under a load in higher gears. Going back one step on the advance curve, I then mixed a heavy silver with a light silver, and the pinging went away, completely.

When I tried the non-timed vacuum port, my idle went up and into an rpm range that overlapped the mechanical advance just coming in, and when I dropped the idle screw down to compensate for it, the engine simply did not seem to want to idle as predictably. This was because the non-timed vaccum force does obviously waver with a Z-11 cam's rough idle, and thus timing jumps around a bit.

Going to the timed vacuum port, gives a steadier crank-timed spark at idle rpm's, which you can very easily adjust a final idle speed for, especially when running an automatic tranny like my 700R4. And, with the advance curve shifted to kick in at a lower rpm (just off idle is best) and at a greater rate of increase, the transistions from idle to cracking the throttle part or even wide open, and then letting the engine go back to a nice steady idle, is seamless.

I can put my '55' in "drive", nail it wide open, then abruptly lift my foot off the throttle, stomp on the brakes, and the engine does not sputter.. it simply drops back to a nice steady idle, still in gear.

That's the difference I found in my application, and the rationale for explaining it.

Oh, and as Ronnie noted, my carbs (600cfm's) are 1405's not 1404's... thanks again Ronnie
(I'm setting up a 2x4 Vortec Endurashine Air-gap on my ZZ430 probably going into my 31 Chevy, and it'll run 1404's... whoopie!)

Lend me your thoughts!

Denis

[dq409]

Denis,
I would say with your engine combo, 409/446 stroker, with 2-600 cfm Edelbrock 1404's, and 11:1 compression, with a hydraulic Z-11 cam, you are running a bit lean on your secondary jetting. Could even be a little lean on your mains.

Try a larger jet and I would bet your performance will increase. That jetting is a starting point on a stock/mild 409. JMO

Also remember that you are at sea level and Boise is at 2400 feet so Nuts need to be a little leaner then us down here at ocean level :D

Nuts, use your Edel carb tuning book and try a different color metter rod spring to see if it smooths out that hesitation.
But you should gett that distributor curved first.

Isn`t this engine dialing in stuff fun !!! ?????:doh (hair pulling out smillie)

[desapience]

Denis,
I would say with your engine combo, 409/446 stroker, with 2-600 cfm Edelbrock 1404's, and 11:1 compression, with a hydraulic Z-11 cam, you are running a bit lean on your secondary jetting. Could even be a little lean on your mains.

Try a larger jet and I would bet your performance will increase. That jetting is a starting point on a stock/mild 409. JMO

Also remember that you are at sea level and Boise is at 2400 feet so Nuts need to be a little leaner then us down here at ocean level :D

Nuts, use your Edel carb tuning book and try a different color metter rod spring to see if it smooths out that hesitation.
But you should gett that distributor curved first.

Isn`t this engine dialing in stuff fun !!! ?????:doh (hair pulling out smillie)


I was toying with the idea I might be running just a tad lean... the plugs are burning chocolate brown, but, the engine temps are a bit warmer than I would like. what do you suggest for secondaries and primaries?

Thanks,
Denis

[Ronnie Russell]

Denis, I would agree with dq with his opinion on jet size, but Ive got an idea who suggested the jet sizes you are using. What works,, works. No doubt you have researched the ignition and experimented until you hit it on the head. Nice work. Your suggestions will give new MSD owners some good pointers.

[desapience]

Denis, I would agree with dq with his opinion on jet size, but Ive got an idea who suggested the jet sizes you are using. What works,, works. No doubt you have researched the ignition and experimented until you hit it on the head. Nice work. Your suggestions will give new MSD owners some good pointers.

Ronnie,

Yep, you know who recommended the jets sizing, but, he (they) also noted it as merely a starting point. But, like I said previously, I did check the plugs, and they burn chocolate brown... maybe a tad light brown. I will try to step them up a bit, not so much for a performance gain, but, in an effort to lower the operating temperatures of the engine overall.

Keep in mind too that I am not yet using tube headers. I am using the 65 409/400hipo cast iron headers in my '55'. They simply fit well, while still allowing for good power, and adapted fairly easily to my steering shaft for the R&P steering.

Now, with my next stroker being built as we speak.. the stroker with a 454 crank, 060" over, and the custom Comp cams roller cam... I definitely will be looking to go significantly larger with the jetting. What would you suggest as a good starting point for the 482 stoker? I'll be using 2x4 1405's and another MSD 8393 on it too, set-up the same as on my 446.... But, as for what headers I'll use with the 482, I'm still up in the air about that.

Thanks again,

Denis

[Ronnie Russell]

Denis, I know it sounds too simple, but for that combination, I like the standard .100s and .095s with the 70x47 rods. Good luck with it and keep us posted.

[desapience]

Denis, I know it sounds too simple, but for that combination, I like the standard .100s and .095s with the 70x47 rods. Good luck with it and keep us posted.

Ronnie,

I agree. I was thinking the same thing... use the 1405's, as is, out of the box as my starting point for the 482.

But, for the 446, I'm going to first go only back halfway richer, maybe .098" primaries, and .089" secondaries... trial and error usually is the pay-off.

I'm going to bring the basic timing from 12 to 13 BTDC and install the slightly larger jets this week. I'll keep the forum updated as to my results. Fine tuning the 409.
Thanks,
Denis

[dq409]

Denis, Your spark plug reading may only show idle and cruse burn.

IMO,,I would up the secondaries and meter rods on the power side and bet you see improved performance in that range.

you are getting good info from others running engine sizes closer to what you have.

On that new engine you are building I would recommend spending a little bit more on the carbs and go with the AVS`s !!
You will be pleasently suprised on how much a better carb they are !!!:brow

,,dq

[desapience]

Denis, Your spark plug reading may only show idle and cruse burn.

IMO,,I would up the secondaries and meter rods on the power side and bet you see improved performance in that range.

you are getting good info from others running engine sizes closer to what you have.

On that new engine you are building I would recommend spending a little bit more on the carbs and go with the AVS`s !!
You will be pleasently suprised on how much a better carb they are !!!:brow

,,dq

Ahhh... I swear you are readng my mind! The entire intake/carb set-up is already done for the second storker (482).. ceramic-coated intake, 2-1405's (with out of the box jetting untouched).

I already posted a pic of this intake on the following thread. Note that the waterneck is set-up to be used with the new Griffen x-flow I'm planning for to tame the temperatures of that 409/482 puppy!

http://www.348-409.com/forum/showthread.php?t=6789

So, my plan for this coming weekend was to simply swap out these "brand new" 1405's for the ones already on my '55' Belair, and sell off the one's that are now in the Belair (they are only rejetted, .086" secondaries, .095" primaries), along with the original jets. They have only about 650 miles on them... as good as new. It's easier to simply swap them out than to rejet the ones already installed on the '55'. It's too hot here now to futz around with jets in a hot garage.

And, yes, I am going to buy a pair of the newer AVS, 650 cfm carbs (18054's, with Endurashine and single inlet on each)... and use the out-of-the-box jetting as a starting point for the 482 stroker (which will eventually find its way into my Belair in the Fall).

I will keep you posted during the weekend.

Denis

[Skip FIx]

One thing you guys might think of investing in is a wide band O2 sensor for dialing in the carbs. It wil REALLY open your eyes where your mixture is and help tell what circuit is lean or rich. The LM-1 is about $350, I've spent more time and parts chasing tuning than that on a motor.

I was chasing an off idle hesitation with accelerator pump cams, jetting until I finally threw on the wide band on the car. In park idle was perfect good vacuum, 12.8-13.1 AFR-slightly rich. BUT in gear there was enough load it leaned out to 16.5. Fattened the idel circuit up , no hesitation!

Back to thr MSD- they are nice precision machined pieces. The springs allow what rpm the total centifical comes in. If the light springs where causing pinging cruising it would be because all the centrifical is in at your cruise rpm and the added vacuum is too much. the stiffer springs just delay when total comes in, maybe above your crusie rpm. They have limiting busings for total centrifical and also I think for the total vaccum. At high vacuum on cruising you will have almost all of it in. I would wonder if you didn't have that going ion and need to limit vacuum total advance.

When I was racing NMCA they had a vacuum rule they factored HP on for your cam. Most guys used direct ported to a vacuum advance to have iton at idle and a very quick curve in the distributor.

Along the 409 distributor line I have one I got with a motor that had a plate with a cable to use as a high speed retard, before there were MSD boxes to do that. It looks almost factory.

desapience-your box is full.

[desapience]

One thing you guys might think of investing in is a wide band O2 sensor for dialing in the carbs. It wil REALLY open your eyes where your mixture is and help tell what circuit is lean or rich. The LM-1 is about $350, I've spent more time and parts chasing tuning than that on a motor.

I was chasing an off idle hesitation with accelerator pump cams, jetting until I finally threw on the wide band on the car. In park idle was perfect good vacuum, 12.8-13.1 AFR-slightly rich. BUT in gear there was enough load it leaned out to 16.5. Fattened the idel circuit up , no hesitation!

Back to thr MSD- they are nice precision machined pieces. The springs allow what rpm the total centifical comes in. If the light springs where causing pinging cruising it would be because all the centrifical is in at your cruise rpm and the added vacuum is too much. the stiffer springs just delay when total comes in, maybe above your crusie rpm. They have limiting busings for total centrifical and also I think for the total vaccum. At high vacuum on cruising you will have almost all of it in. I would wonder if you didn't have that going ion and need to limit vacuum total advance.

When I was racing NMCA they had a vacuum rule they factored HP on for your cam. Most guys used direct ported to a vacuum advance to have iton at idle and a very quick curve in the distributor.

Along the 409 distributor line I have one I got with a motor that had a plate with a cable to use as a high speed retard, before there were MSD boxes to do that. It looks almost factory.

desapience-your box is full.


I deleted most of my mailbox messages, sorry about that!

First, given what others here are experiencing, my particular problem is a minor one -- albeit, I will chase down even the shortest skirts.

The sensor idea is valid and surely would be worth the "eye-opening" education it would provide. In fact, I'm going to take your suggestion and get one!

But, before I put it to work, I'm going to follow the logic of all the discourse here, and see if I can solve the problem at least to a level of my personal satisfaction. Then, I'll check those results against what the sensor unveils.

I'm more than game for coming up with a sort of "fine-tune" formula for the MSD 8393 in my 409/446 stroker combo... and, I'll share all the results when I have them.

I believe the MSD has only a vacuum lockout, but, as I write this, I'm not certain of that... need to check the manual on that.

It's gonna be a hot weekend in the garage though... may have to do a 6-am spurt to avoid the worst of it.

Thanks for the input,
Denis

[Nuts]

All,

Thanks for all the advice and knowledge... :clap

This morning I recurved the distributor mechanical advance. I used one "light silver" and one "Light blue" spring from the MSD box. Most of the hesitation is gone and I don't hear any pinging or detonation while driving and I tried to load it up, but was driving on flat roads. She still has a slight hesitation coming off idle but that could be carb adjustment ?? I let her idle in the driveway for approx 20 min. and the temp stayed about 190, so that's good news.

I believe the initial advance is 12-13 degrees and I'm getting 2-3 degrees of mechanical advance for a total of 15 degrees at 800 rpm idle. With vacuum disconnected I get 33 degrees of total advance (inital + mechanical) at 2800 rpm and that is at the stop, doesn't go up after that. With the vacuum hooked up to manifold vacuum I get 23 degrees at idle and 43 degrees at 2800 rpm.

As I said, there is still a slight hesitation coming off idle and once when I let off the throttle real quick she almost died. :dunno After running in the drive for a few minutes I get a puff of black smoke out the tail pipes that clears right up. The plugs are all black with some slight deposits, but she hasn't been on a long drive lately.

Now I believe, I need to look at the carbs so a couple of questions. I'm running both carbs right now (Edelbrock 500) with no progressive linkage. To adjust the carbs do I need two vacuum gauges hooked up ? Do I hook up to the manifold (left) port on both carbs ? Never done this daul carb adjusting thing before !!!! :dunno

If I go with a progress setup, what do I do with the idle mixture adjustments on the front carb ?? Also, will this cause the car to run lean on the front half of the motor ?

Curious mind need to know.... Looking for your knowledgeable responses...:hug

[fatride]

One vacuum gauge hooked to manifold vacuum will do.

Modifications needed to run new style 600 Carter or Edelbrock carburetors.

New Edelbrock and Carter AFBs are identical carbs. Under the carb use either a 1" spacer with open plenum or Edelbrock #2732 plate. The new style carbs will develop a vacuum leak under the carbs without this. We recommend 600 cfm manual choke carbs since they react to jetting changes better. Remove .100 or .101 primary jet and put .095 secondary jet in as primary. Put .086 jet in as secondary. Use the 7047 metering rod. Adjust each idle mixture screw out one turn and each throttle out 1.5 turns. Adjust each idle screw to obtain maximum vacuum and then adjust throttle screws equally to obtain idle speed. DO NOT adjust idle mixture screws all the way in on front carb. Use the lightest metering rod springs that does not surge at highway speeds (usually 5" to 7" below idle vacuum - if engine idles with 12" vacuum try 5" springs first in both carbs). .

[desapience]

One vacuum gauge hooked to manifold vacuum will do.

Modifications needed to run new style 600 Carter or Edelbrock carburetors.

New Edelbrock and Carter AFBs are identical carbs. Under the carb use either a 1" spacer with open plenum or Edelbrock #2732 plate. The new style carbs will develop a vacuum leak under the carbs without this. We recommend 600 cfm manual choke carbs since they react to jetting changes better. Remove .100 or .101 primary jet and put .095 secondary jet in as primary. Put .086 jet in as secondary. Use the 7047 metering rod. Adjust each idle mixture screw out one turn and each throttle out 1.5 turns. Adjust each idle screw to obtain maximum vacuum and then adjust throttle screws equally to obtain idle speed. DO NOT adjust idle mixture screws all the way in on front carb. Use the lightest metering rod springs that does not surge at highway speeds (usually 5" to 7" below idle vacuum - if engine idles with 12" vacuum try 5" springs first in both carbs). .

Guys,

Finally had the chance to changout my carbs -- the 1405's I had at the ready for my upcoming 482... they remained with the stock jetting of .101" primaries and .095" secondaries. REPORT: My 446, loves this jetting, so far! The linkage is set as NON-progessive.

The '55' fired right up -- in my garage -- it's 90- dregrees outside and extremely humid (raining)... I did not even have to touch the idle speed -- nothing. I set my fuel pressure to 7.8# (which goes down to 7.5# on the run). There is absolutely no hesitation, and no stalling after a quick stomp and let-off, while in drive or otherwise (700R4 auto tanny). It idles at 900 rpm, and in drive at ~600.

I left it running... in a hot stuffy garage with no fans blowing on the grill-work to help cool it.

She warmed right up.. went to 200, where I have my Dakota Digital fan controller set to kick-in... and the fan did excatly that, on que.

The good news, is that once the fan cut-in, it brought the temp back down to 195, where the fan is set to cut-off, and it did cut-off, on que! I may re-program the Dakota controller to cut in a bit sooner and cut off .. say 195 for on, 185 for off. I have a 160 stat.

Since it's raining a bit, I have not been able to take it out on the road (this car will never see rain again). So, I have not been able to check for any surging, but, with the jetting I was using -- as stated above -- .095" primaries, .086" sconedaries -- it did not surge, but in retrospect, it was obviously running a bit lean...

The out-of-the box jetting for 1405's, is a dramatic improvement in running temperature. Running in the garage like this, it would have over-heated in a heart-beat with the other jetting, and I am not getting black smoke at all!

I'll be going forward to buy the 18054's (AVS 650's w/Endurashine) for my upcoming 482, so the carbs I had on my '55' are formally FOR SALE now -- as new -- and will include all paperwork in the Edlebrock boxes, new gaskets, and the stock jetting as well as the .086's. There is absolutely nothing wrong with them -- and have only ~650 miles on them!

They'd be perfect for a stock/mild/or wild 409/446 stroker -- you'd have all the jets for those applications! MAKE AN OFFER!

I'll update again after I take it out for a good spin...

Denis

[dq409]

Good news for a couple of you !!!:D :clap

[Nuts]

Desapience and Fatride,,

That is some great technical information, I just wish I was enough of a mechanic to translate it into English.... I know that the jets have been changed out in the carbs from what they came out of the box, I'll have to dig into the Dyno notes to figure out what size they are. He told me that he had put in the smallest that Edlebrock made for the 500s.

Because the car acted like it was running very rich I decided to try it with a progressive linkage. It seemed to run okay at higher speeds but would not idle and loaded up something terrible at the lights. It also sent the temp up quickely at speeds over 65 mph ??? So I believe it was running very lean on just one carb.

I would like to be able to run a progressive linkage to see if that will help with the MPG, which is in the tolet right now. I believe I'm getting less than 9 MPG currently and that's with light driving, not pushing through the gears.

I already have plates under the carb like the EDL 2732. Two plates and three gaskets. Don't know if that is helping or increasing the problem ??? :dunno

[MRHP]

I don't know if you had checked to make sure your front and rear idle screws are turned the same amount once the throttle plates start to move. If one is open more than the other you make a vac. leak and will idle poorly and have a throttle tip in hesitation.Also, try your accelerator rods in the center hole or the farthest hole from the carb. Hope it helps! Brian

[Ronnie Russell]

Nuts, The front carb needs to be involved in the idle process. Is it possible that the idle screw on front carb is completely screwed all the way out? I have found out that setting front and rear idle screws the same provides best idle and off idle response. In other words , you may have to back off rear carb idle screw and increase front carb screw. That may or not be your problem, but you might want to check that.

[Ronnie Russell]

Sorry, I didnt read close enough. MRHP had already covered that suggestion.

[MRHP]

HA! Great minds think alike Ronnie.

[desapience]

Desapience and Fatride,,

That is some great technical information, I just wish I was enough of a mechanic to translate it into English.... I know that the jets have been changed out in the carbs from what they came out of the box, I'll have to dig into the Dyno notes to figure out what size they are. He told me that he had put in the smallest that Edlebrock made for the 500s.

Because the car acted like it was running very rich I decided to try it with a progressive linkage. It seemed to run okay at higher speeds but would not idle and loaded up something terrible at the lights. It also sent the temp up quickely at speeds over 65 mph ??? So I believe it was running very lean on just one carb.

I would like to be able to run a progressive linkage to see if that will help with the MPG, which is in the tolet right now. I believe I'm getting less than 9 MPG currently and that's with light driving, not pushing through the gears.

I already have plates under the carb like the EDL 2732. Two plates and three gaskets. Don't know if that is helping or increasing the problem ??? :dunno

Nuts,

Please go over for us all what exactly your enigne is built out as.
1. IS it a 409 with hipo heads?
2. What's the over-bore, if any, what's the stroke, and compression ratio?
3. Which cam are you running -- give us all the specs on it if you know them?
4. What tranny are you running and rear-end ratios?

Assuming you have a mild cam, stock bore and stroke (409 c.i.) and around 10.5 or 11:1 compression, why did you go to Edelbrock 500's? And, assuming that's correct, why would anyone want to go to the "smallest jets available" for the 500's?

And, lastly, what distributor are you running and what's the initial timing set at, and do you have a vacuum advance and which port is iti attached to (timed or non-timed)? Also, if it is an MSD 8393, which advance springs did you put into it?

After we get all those details, on one list, I think we'll all have an easier time getting to the root of your problems -- just don't give up on the 409, or us.

Denis

Denis

[Skip FIx]

Here's the site for the LM-1 that I have been using. They have alot of good info on carb tuning. www.innovatemotorsports.com

Remember on a Carter (or Qjet) cruising mixture is realted to rod/jet difference(Holley just jets). WOT primary runs tune your primary jetting. Full WOT dial in secondary jetting. Quick WOT tell you where your accelerator pump circuit is. On a AFR meter you wil always get a lean spike even if you can't feel a bog, meter reads faster than carb can react,so you don't need to go crazy trying to get that out.

"Ideal" for emissions AFR is 14.7, most engines for power like 12.5-13.3. Higher numbers leaner, lower numbers too rich.

[Nuts]

All,

Here are the specifications as I know them. Remember that I can't know what I don't know, so if there are other questions please let me know. I appreciate everyone's help with this...

Engine : 1963 passenger block bored .30 over
Ross pistons 10 to 1 with valve releif cut in
817 heads - Int = 2.195 Exh = 1.725
Valve springs = Isky 31:05 - D Dia = 1.55
Cam = Isky Custom Hydraulic Calculated with 1.7 Rocker Ratio
Duration = 234/234 @ .050
Cam Lift = .300/.300
Valve Lift = .510/.510
Lobe Center = 110

Intake : OEM 2X4 manifold
Edlebrock 500 carbs (Adjusted by Dyno for most HP)
83 X 86 Jets
6552 Rod, Orange Spring

Distributor : MSD 8393 Electronic with OEM type (female) cap
Initial Timing = 13-14 degrees
One Light Silver and One Light Blue spring
Vacuum hooked to ported (right) rear carb
Manifold vacuum at idle = 7-9 in. @ 800 idle

Trans/Rear : M21 Muncie (Close Ration) / 3.08 open (I like to cruse the Hwy)

I changed back to ported vacuum from manifold yesterday and she runs alittle better today. Seems to run alot better when cold and developes a hestitation when the coolant temp gets above 190 degrees.

Sure wish I could have one of you guys in my hip pocket for a couple of days... :hug I'm sure that hearing it run would be a lot better for diagnosis.

DQ - Bring yours out, we'll park them in the AC'd shop and fix both of them !!!! Only a few hours drive, you know !!! :)

[dq409]

All,


DQ - Bring yours out, we'll park them in the AC'd shop and fix both of them !!!! Only a few hours drive, you know !!! :)


BOY,,, You don`t know how tempting that offer is !!!:bow

She`s sitting OUTSIDE in the driveway with nowhere to work on her and unsecure !!

I dread every moment I`m not home,,,:mad:

[fatride]

Nuts, how far in the hole are your pistons? What head gasket are you using? Loose the orange stepup springs, replace them with the blue ones.

[Nuts]

Fatride,

"How far in the hole are the pistons ???" Now there's a question I have no answer for.... I can tell you that the deck clearance, measured by me, with NO IDEA of what I was doing, was close to Zero.

The head gaskets are FelPro Perm-a-Torq...

I could loose the springs - but I've no idea where they are, or where to get blue ones ??? :dunno

Remeber I can turn a wrench, most of the time in the correct direction, but am not really a mechanic. :rofl

[dq409]

Fatride,

"How far in the hole are the pistons ???" Now there's a question I have no answer for.... I can tell you that the deck clearance, measured by me, with NO IDEA of what I was doing, was close to Zero.

The head gaskets are FelPro Perm-a-Torq...

I could loose the springs - but I've no idea where they are, or where to get blue ones ??? :dunno

Remeber I can turn a wrench, most of the time in the correct direction, but am not really a mechanic. :rofl

Nut, You don`t have to be too smart to work on these carbs.
Those springs are just under the two screws on the top of the carbs just on the outside of the front ventura ports
Just take your time and you will see how easy it is,,
You can get the springs at any parts house that sells Edelbrock stuff ,dq

[Nuts]

Looks like everyone but DQ and I have lost interest in this thread.....

I took the car out for a drive in the 100+ degree heat yesterday. She ran along at 180 on the highway at 50-55 MPH with the AC turned off. I turned the AC on and she stayed under 200 until I got into the traffic on the return trip. I was able to sit at the lights and she stayed under 210, so it looks like the current setup getting close to right. :) I still have an electric fan coming that should help the traffic situations so I'm making progress. And yes, I understand that these temp are in range, just the top end.

I did have one problem on the drive... After driving down the highway for about 10 miles, I went to turn around and she just died. I tried to start using the clutch but no go. I pulled over and she started right back up. :dunno After that I let the motor come down in RPMs slower by down shifting and didn't have the problem again. :dunno

[dq409]

I try to never lose interest !!:rofl

Sounds like you are almost there on the temp thing.:clap

I think once you get the elec fan your problems should be solved as they really work good when the rpm`s are too low for the engine fan to keep her cool.

That other problem is weird.

If it happens again i would check your float levels. It could just be a fluke or from your explanation just stalled it by lugging her. dq

[Ronnie Russell]

Nuts, 210 with A.C. in traffic? Many would like to have that problem. The electric fan should finish you up. Congratulations on staying with it. The stall problem was just the car letting you know that ...." They are never completely finished"... Keep on , Keeping on. You are almost there.:)

[Nuts]

Ronnie,
Thanks for the kind thoughts.... I'm making positive progress, so that's better than I usually do. I just hope I get there by the planned trip to Minneapolis for the LGC convention in August...

I had the oil today and put in 20/50 non-syn and a new filter. The oil pressure is holding around 40 psi at 190 so that is alot better than the -10 I was getting with the other oil. The car really gathered a crowd at the Jeffy Lube, there were a number of kids working who had hot rod trucks. They peer pressured me into a burn out, so on the way out I lit them up. Even with the 3:08 rear end, she will lay down a pretty good strip !!! :) :cool:

BTW - I take them the oil and filter and only let them change the oil under my supervision... It's just too hard to get rid of the old oil in Idaho, and they only charge me $20. Saves me time laying on my back on the shop floor besides... :clap

[desapience]

For those of you who have been following my temp/carb/jetting issues, I did in fact change BOTH my present 1405's (with their .095 primaries, and .086 secondaries) for the entire new set of 1405's (which were set aside for my upcoming 482 stroker) with out of the box jets (.100 primaries and .095 secondaries). I changed nothing else (but the other 1405's are for sale as a duo.. check my "for sale" ad).

I took the '55' out yesterday evening, and the car was running about 10 degrees COOLER! My electric fan is controlled by a computerized Dakota Difital fan controller (highly recommended), and it was set at 200 on, 195 off.... with a 160 stat. The engine temps, in 90+ degree weather yesterday, stuck at about 200-205...

So, this evening I re-programmed the Dakota Digital fan controller (it reads temps directly off my electric autometer gauge). I ran the engine in my garage for 20-25 minutes, with no fans blowing air on the grillwork.

The fan kicked in on que, at 185, and stayed there... the temp did not go up or down from that point, so the "fan-off" temp did not reach 180 to turn the fan off. I did not have a chance to take the car out for a run.. but, it's easy to assume that with a flood of cooler air hitting the radiator, I will see the temp osscilate between 180-185... meaning the fan would be turning on and off -- AND, more importantly, that I have gained full control of the engine's running temp, an no longer the engine alone or outside temps having that control!

Also, in the rejetting, the car no longer diesels out at all... I used to turn the engine off while still in drive to keep it from running on. I no longer need to do that... another direct sign that the engine is running a lot cooler.

Next, I'll be playing a bit with the timing... one negative thing I picked up with the re-jetting, is that upon a quick return to idle (as when making a turn), the car did bog and even stalled one time... The idle was set a bit too low still, so, I reset that upwards a tad today and that alone may take care of it. I seriously doubt that in my case, that it' s a float level problem.

I also will try to set my basic timing to 14... see what happens there. And, I'm going to play a bit with using a non-timed vacuum port... but, I do not want to necessarily get beyond a 20 degree initial..

One step at a time... lots of trial and error... but, I'm VERY close to my optimum.

Denis

[mac1]

They peer pressured me into a burn out, so on the way out I lit them up. Even with the 3:08 rear end, she will lay down a pretty good strip !!! :) :cool:

Don't you just love it when they ask you to light em up. :)

Just a quick pic of a perma cool fan I installed inside my fan shroud this weekend. I know I'm not the first one to do this. It's a perma cool 18" 2500 cfm 30 amp fan http://www.perma-cool.com/Catalog/Cat_page16.html
that comes on when the a/c is turned on by a relay and also by a toggle switch under the dash that goes to the same relay. It will cool the engine about 10 degrees on top of the stock fan. The clearance is good around the shroud but very close to the stock fan, about 1/2" at the center hub. I like it there as apposed to the front of the rad as you really don't see it unless your looking for it. If you do this make sure they both turn in the same direction. I hooked them up on my 327 rotating in opposite directions and
man that motor got hot!:doh BTW, I using a 2" fan spacer. Mac

http://img.villagephotos.com/p/2003-9/394748/HLTWY-DSCF0001.JPG

[JimKwiatkowski]

For those of you who have been following my temp/carb/jetting issues, I did in fact change BOTH my present 1405's (with their .095 primaries, and .086 secondaries) for the entire new set of 1405's (which were set aside for my upcoming 482 stroker) with out of the box jets (.100 primaries and .095 secondaries).

Denis

Denis,what jets are you using in this last road test .095 and .086 or .100 and .095?

[Tom Kochtanek]

Nuts, I had to laugh when you mentioned "... It's just too hard to get rid of the old oil in Idaho, and they only charge me $20".

We have a standing joke about Ebay (started by Tom Collins, aka "Wrench"!) that with 409 prices going through the roof on Ebay, why not offer to sell that "valuable" 409 oil to some lucky bidder who just needs another piece of nostalgic 409 history on their shelf?

Just kidding, but with all the craziness I bet someone (not me!) would actually bid on it. Now try to get the $$$ sent, that's another story...

Enjoy!
TomK

P.S. I seriously saved all the metal dust created when I used the die grinder to "relieve" lower portions of my truck block when fitting up the stroker crank :). I keep it right next to my pouch of salt from the Bonneville Salt Flats in Utah in my lock box...

[dq409]

why not offer to sell that "valuable" 409 oil to some lucky bidder who just needs another piece of nostalgic 409 history on their shelf?

P.S. I seriously saved all the metal dust created when I used the die grinder to "relieve" lower portions of my truck block when fitting up the stroker crank :). I keep it right next to my pouch of salt from the Bonneville Salt Flats in Utah in my lock box...TomK


You guys are SICK REALLY SICK !!!!:doh













BTW,,,, How much do you want for that 409 metal dust !!!:rofl

[desapience]

Denis,what jets are you using in this last road test .095 and .086 or .100 and .095?

The jets, rods and staging springs I'm using are what comes out-of-the-box for Edelbrock's 1405's. Here's the reference calibration chart for it.

http://www.edelbrock.com/automotive/eps_1405.html

It has .100" primaries, .095" secondaries, and 1451 (070 x 047)* rods- stock calibration (*Some Have ID #695)

If you go to the bottom of this link-page, and click on "Back to Table of contents", and once at the table of contents, go to "Section 2" and under it, click on "Calibrating the power mode staging", you'll get to the discussion of the staging springs.

The out-of-the-box staging srping is what I'm using -- Orange 5"Hg.
I have absolutely no surging going on as is, now.

I PM'd this and much more to you last night... update me as you go.

I got the 18054's (w/Endurashine) delivered today... gorgeous carbs, really!

Out-of-the-box, the 1805's have .095" primaries and .098" secondaries, and an ajustable airvalve. The rods are 1447 (.068" x .047").... so, it looks like when I get my 482 running, I'll be playing with jets, once again! :cuss

Denis

[desapience]

Once again, for those who have followed the running temperature, jetting and timing issues I'm dealing with, here is yet another update.

Changing to richer jetting on my Edelbrock 600's (1405's), going from .095" primaries to .100" primaries, and from .086" secondaries to .095 secondaries provided a significant change in that my running temperatures did drop... but, when I did take the car out for a good spin, I found the drop was still leaving me running hotter than I wanted (205--215).

Further seeking to run cooler, I changed the programming on my Dakota digital fan controller, so that the fan kicked-in sooner at 185, and off at 180. Taking the car out for another spin in hot weather (90-93 degrees and humid), showed that although it took much longer to get to 205-215, it still reached those same high temps (which makes sense).

So, I went to the timing, and timing curve to look for more engine efficiency. The more efficient an engine runs, the more power it makes and the less heat left over to heat up the engine components and the coolant, right?

I double-checked my basic crank timing -- 13. Then, I took the MSD 8393, and hooked it up to a non-timed vacuum port (it was on a timed port above). That change took me another 15.5 degrees advanced, at idle, for a total of 28.5, which is a bit high for my taste (I'll go back to 12 basic to get back one degree, and possibly go to an adjustable vacuum cannister pot, as needed).

But, with the fan controller programming unchanged (on at 185, off at 180), I took the car out for another spin (at 93 oustide temp), and the engine temp did NOT go over 190, and in fact hoovered between 190-185! There was also absolutely no pinging, or surging, regardless of high-gear load! The engine also ran much stronger, and there was absolutely no engine run-on (deiseling) when the engine was shut down (out of gear). I'll reprogram the fan controller to match whatever temps I finally end up with, later.

The sole issue remaining, was that the engine bogged a bit, on making a quick turn, with a quick return to idle speed. But, again, my idle setting, in gear, is a bit low. I do not believe it to be a float-level problem (I was also running low on gas in the tank -- sloshing away from the tank's pickup may be the problem).

So, I need to sort it out a bit more. But, without a doubt though, connecting my MSD to a non-timed vacuum port, resulted in a much more effcient running engine (more power) and thus less wasted heat energy to cool... thus, running cooler!

And, NO black smoke!

The next trial will be to play with the mechanical advance curve. Since there was no pinging with one blue and one heavy silver (as above), I'm going to try going to the next WEAKER mechanical advance spring parings -- for a quicker shift into the advance curve, and a greater rate of increase of the mechanical advance (a steeper curve).

So, I'll first try to go with two blues. If there is no detonation (pinging), this quicker shift, and rate of increase of the mechanical advance, should work to covert even more excess heat energy into power, resulting in an even more efficient power cycle and a cooler running engine. If there remains no pinging (with two blues), along with an accompanying relative lower running temperature, I'll go to the next weaker spring set (one blue, one light silver), and try again. If it pings, I'll go back to the two blues, confident that I have the most efficient combination of jetting, timing, and advance settings, for my particualr engine combo.

Trial and error...

Denis

[IgnitionMan]

Absolutely Amazing, Incredible. Nobody's Ever Outlined Doing It That Way Before, Just............nobody.

[Nuts]

Denis,

Thanks for all the information... and congratulation on finding an answer for most of your problems!! :clap :) I'm following your posts with interest, as you know I'm having the same problems. I have a couple of questions though ???:dunno

What do you have for vacuum at idle, on both the ported and manifold ports ?

Are your running a progressive linkage or solid ?

Did you re-jet both carbs the same ?

[desapience]

Denis,

Thanks for all the information... and congratulation on finding an answer for most of your problems!! :clap :) I'm following your posts with interest, as you know I'm having the same problems. I have a couple of questions though ???:dunno

What do you have for vacuum at idle, on both the ported and manifold ports ?

Are your running a progressive linkage or solid ?

Did you re-jet both carbs the same ?

Nuts,

Being that I have a 700R4 tranny, there are two idle vacuum measurements: one in gear, and one in park or neutral.

I set my park/neutral idle at 975-1000 rpm -- and has 12 mm Hg vaccum there (remember, Ihave a Z-11 hydraulic cam).

My in grear idle falls to 650-675 rpm -- and has ~6mm Hq vacuum there.

Vacuum is vacuum, whether it's sourced from a timed or non-timed port. the difference is one is constant (non-timed), the other (timed) comes into play only when the throttle plates are cracked open.

I am not running progressive linkage -- it's solid. I did have it set on progressive, but, the engine was a bit harder starting that way (uneven fuel distribution?). Gas milage takes a dive with a solid set-up, but, my car is more of a show-car and is not driven except to two weekly cruises and yearly show events. And, with the solid linkage setting, the car is awesome coming off the line... absolutely no hesitation, instant power... and the engine fires right up, without any choke, and no black smoke.

Both of my 1405's are jetted exactly the same. My stoker 446 runs better -- and much cooler -- now with the richer .100 primaries and .095 secondaries than it did with the .095 primaries and .086 secondaries. The rods are out-of-the-box 1451(.070 x .047), and the staging springs are also out-of-the-box 5" (orange).

As I mentioned previously, the only negative result I've had come about with going to richer jetting, is the "bog" I got when I made a quick return to idle upon taking a turn. I also mentioned that the bog may be the result of my gas tank pickup coming up dry, because the tank was low on fuel at the time.

So, I have yet to figure that out... bogs can result from being a bit lean, or a bit too rich. The engine DOES not surge though, not at all -- which, if it did, then I'd be pretty certain the staging spings were not heavy enough.

I'm just going to have to fill my tank and go out and try to see if I can rule out or in if the fuel level was the problem. If it's not the fuel level, then, I'll need to play a bit with the staging springs... try one step heavy, and/or one step lighter. If that does not change anything, I'll have to go back to the calibaration reference chart and try to go up rich, and/or one step lean with the rods/jetting. I've ruled out the fuel pressure setting, and the float level setting.

Alternatively, I can use an Ari/Fuel ratio sensor, to get a reading on which way to go (leaner or richer). That would reduce the "playing around", and trial and error method.

I am already real close though... real close.

My next area may be to go to an adjustable vacuum cannister. As it is now, the non-timed vaccum give me 15.5 degrees over my basic timing (13-14), which is a bit much given that my overall is around 35-36. I'd prefer to get about 20 or less total with vacuum and basic timing... but, it runs so strong now, that if I can pin down the bog problem with changing staging springs and/or rods, I'll likely leave all else alone.

I hope this all helps...

Denis

[fatride]

Denis, if you are surging at cruise or runing rich at idle you would go with a lighter step up spring. If putting the tranny in gear pulls you idle rpm down 350/400 rpm to a point where you are only pulling 6" of vacuum I would try to get more initial timing in the engine. With more initial timing the idle should not pull down the rpms as much when placed in gear , try 20/23 dgs initial. With this much initial I would adjust the vacuum pot to a point where you would not be pulling additional advance at idle when hooked to a manifold vacuum source. Adjust the vacuum pot to pull additional advance at 15/18" of vacuum. With 36/38 dgs total add enough vacuum advance for a cruise advance of 47/50 dgs. You need to bring the vacuum at idle up a bit. If you have only 6" of vacuum at idle you need to install the blue step up springs.

[desapience]

Denis, if you are surging at cruise or runing rich at idle you would go with a lighter step up spring. If putting the tranny in gear pulls you idle rpm down 350/400 rpm to a point where you are only pulling 6" of vacuum I would try to get more initial timing in the engine. With more initial timing the idle should not pull down the rpms as much when placed in gear , try 20/23 dgs initial. With this much initial I would adjust the vacuum pot to a point where you would not be pulling additional advance at idle when hooked to a manifold vacuum source. Adjust the vacuum pot to pull additional advance at 15/18" of vacuum. With 36/38 dgs total add enough vacuum advance for a cruise advance of 47/50 dgs. You need to bring the vacuum at idle up a bit. If you have only 6" of vacuum at idle you need to install the blue step up springs.

Fatride,

No, the car does not surge at all... but, I agree I'm very likely running a bit rich at idle which is likely the cause of the light bog on return to idle (in gear). I'll be systematically going over everything this coming weekend. I'll be playing with the mechanical advance again a bit (try two blues again), staging springs (blue or yellow), vacuum advance (need to recheck all vacuum readings at various stages, find an adjustable pot), etc.

As I said, I'm real close... and, it's be fun getting there!

I'll update again when I do the next changes.

thanks again,
Denis

[desapience]

Denis, if you are surging at cruise or runing rich at idle you would go with a lighter step up spring. If putting the tranny in gear pulls you idle rpm down 350/400 rpm to a point where you are only pulling 6" of vacuum I would try to get more initial timing in the engine. With more initial timing the idle should not pull down the rpms as much when placed in gear , try 20/23 dgs initial. With this much initial I would adjust the vacuum pot to a point where you would not be pulling additional advance at idle when hooked to a manifold vacuum source. Adjust the vacuum pot to pull additional advance at 15/18" of vacuum. With 36/38 dgs total add enough vacuum advance for a cruise advance of 47/50 dgs. You need to bring the vacuum at idle up a bit. If you have only 6" of vacuum at idle you need to install the blue step up springs.

Fatride,

Well, I went through all the various colors of the staging springs, and there was little to no change no matter if I used the blues, yellows, ogange (stock), or even the pink.

It still bogs on quick return to idle, even to the point of stalling. It shows up particularly when I stop suddenly.

I believe I need to step down a bit leaner on the metering rods 1457 (.073 x .052). If you go to the calibration reference chart, I'm going to focus upon "black dot" #22, first trying to change out only the rods.. and go to the slightly smaller secondary .092 jets only if the problem remains or is only lessened.

Remember, I picked up this bogging problem ONLY after I went from the .095 primaries and .086 secondaries -- to the .100 primaries and .095 secondaries. The rods remained .070 x .047, and the staging springs, orange (out of the box).

Back before I went richer, there was a very slight surging only when the engine was cold, and only at mild initial take off (going to the pink staging springs would have gotten rid of it easliy).

I'll get the four .073 x .052 rods tomorrow. I'll also purchase a set of 4 of the .070 x .052 rods as well. I will also get four .092 jets for the secondaries (if I follow through with the entire recommended combo of black dots #22 or #6.

It makes sense that I may have gone a bit too rich in my initial changes. Backing up a bit may do the trick.

Timing remains another issue (I went to a non-timed vacuum port, but, that too was after I picked up the the bog from the richer jetting)...

I'll get it ironed out. What I'm certain of today is that simply changing the staging springs did not result in anything positive, no real changes.

Here's a link to the calibration chart for quick reference.

http://www.edelbrock.com/automotive/eps_1405.html


Lend me your thoughts and ideas.

Denis

[fatride]

Denis, I think you are a little confused as to what the step up springs function is. They are not staging springs, They are very specific as to the vacuum you have at cruise and idle. Changing from the orange springs to the pink springs is a step in the wrong direction with 6" of vacuum at idle.

[desapience]

Denis, I think you are a little confused as to what the step up springs function is. They are not staging springs, They are very specific as to the vacuum you have at cruise and idle. Changing from the orange springs to the pink springs is a step in the wrong direction with 6" of vacuum at idle.

Fatride,

No, I do understand the step-up function as it relates to idle and cruise vacuum. I went first to the blues.

My idle vacuum a 670 rpm is 5-6"... At 1000-1100 it's 14-15"..

I started all over, beginning with the idle mixture screws, got another 1/2+ turn richer on all 4 screws (best lean idle)..., stayed with the blue step-up springs... and the bog is all but gone -- very noticable improvement.

My fuel pressure has also been a bit erratic, which I kept a very close eye on... kept it at at 5.5 - 6 #.. will clean out the Earl's filter tomorrow as well, and check out all electrical connections to the pump.

Basic crank timing is 14 BTDC.

Tomorrow afternoon I'll go over the timing at in-gear idle, with the non-timed vacuum attached to the MSD. It's the only thing I did not check out and compare to the park-neutral idle timing, with vaccum attached.

The car runs very strong... but, still warmer than I'd like, although it doe not boil over (stays at 205-210), and it is still hot and very humid outside now (88).

I'll go over the all idle mixture screw settings again tomorrow -- more carefully. I believe I could have gone richer by another 1/4 turn, even after cutting back lean 20 rpm. I can also stand another 50 rpm at in-gear idle.

Overall though, I'm even closer to the ideal for my engine. An adjustable vacuum pot for the MSD may be the final touch needed.

Your thoughts?

Denis

[models916]

Stop with the initial timing stuff. Set your total with a tape a 38 and leave it alone. Change the springs in the distributor for the curve and the vacuum for the idle quality. If that does not work, you are looking in the wrong place.

[desapience]

Stop with the initial timing stuff. Set your total with a tape a 38 and leave it alone. Change the springs in the distributor for the curve and the vacuum for the idle quality. If that does not work, you are looking in the wrong place.

Well, actually, it has worked. Throwing a couple new carbs atop a hyped-out 446 stroker does require proper jetting. Refining the timing curve to fit the engine combo is no big deal, but, it all has to match up. And, there's only going to be so much vacuum made by a given camshaft, with optimum idle mixture settings. And, that is what has been accomplished. Outside of that, and with the engine put together correctly, without vacuum or compression leaks or spark problems, there is no place else to look. It's done.

BTW, my overall is 36.

Thanks for the input.
Denis