Carter Comp carbs.

[Ronnie Russell]

Ray, it would be an honor to stick my head under your hood. After last re-build on the glide, trans. man said to never warm up rear end on the jack again. Something about trans. damage. I know nothing about A/T so I cant comment. But we now run up and down the return road to warm rear end.

 

[Skip FIx]

A friend from Tampa has a 64 409 race car that fraggged a TH 400 going into neutral at the end of the track.

 

[SS425HP]

Th400

Had a friend, Dean LaPole that stuffed a TH400 into reverse at the 1/4 mile. Had to. Was on fire. Chutes burned off. No brakes. Stuffed it into reverse at 200 MPH. got stopped, too. Didn't hurt the tranny. His fire suit and underware were JUNK. 1970 at Lion's drag strip. Saw it.

 

[Fathead Racing]

When you purchace a strip kit for dual quads you buy two right ?

 

[Garbageman]

Yes, those are the sizes I'm using.
You have to remember Jim is running Edelbrock Thunder Series AVS carbs not AFBs. This allows him to adjust his secondary air valve to compensate for a lot of changes.

But I agree that with steady increases or decreases in jet size at the track you can see definate results. I guess I'm going to have to pry open my wallet and get a couple of tuning kits for this season.

I did have some good news today. Long story short:
Last year at the track I dropped a valve--only damage was to that valve, spring and guide. Had a shop (drag racer also) repair the damage installed better locks and thicker walled pushrods ( mine were bending) added screw in studs and life was good.

Raced the rest of the season but performance was down. Pulled valve covers--pushrods were deflecting the rockers side to side:eek: Went back to the mechanic and he said the machinist had oversized the Pushrod guide holes in the heads An argument insued. I called Phill and got 3/8 in pushrods and guide plates.
Today it was warm enough to drain antefreeze to pull heads for guide plate installation (milling involved). But before I got the heads off I tryed the 3/8 pushrods and THEY FIT PERFECTLY. NO NEED FOR GUIDE PLATES.
I'm assuming when the mechanic told the machinist he was installing thick pushrods sohe thought 3/8s instead of thick walled 5/16s.

I'm a happy camper now. Any one interested in a set of thick walled 3/8s Smith Brothers pushrods?
Paul

 

[dq409]

Yes, those are the sizes I'm using.
You have to remember Jim is running Edelbrock Thunder Series AVS carbs not AFBs. This allows him to adjust his secondary air valve to compensate for a lot of changes.

Paul

I don`t think the AVS`s adjustable secondaries have much to do with jetting.
They only allow you to adjust the timing of the secondaries opening.
If I remember right i was really close to these jet sizes in my old Edel AFB`s.
I think they were up to .098`s, dq

BTW, Glad to here about the head work/push rods!

 

[Fathead Racing]

Jim, what were the issues you were having with the AFBs that made you switch to the AVS carbs?

 

[dq409]

BOG Off the line. If you watch the convention video you can see that my car bogged off the line then the next pass was better. By the time the third pass I had it dialed in.
it only takes a second to tighten up the secondaries with the AVS`s.
Can`t do it at all with the AFB`s.
before the convention here in Portland I had the carbs running without any bog but at Thunder Valley it came back. Don`t know what the problem was but with being able to tune the secondaries it wasn`t a problem.
I screwed with the AFB`s for a long time tryng to get the bog out but never could.
I would recommend the AVS over the AFB`s anytime.
The small price difference is well worth it.

Paul is going through this and has been the last few seasons. I keep telling him to up-grade to the AVs carbs but he just don`t listen
must be something about living in a rain forest:eek:

 

[jim_ss409]

I'll try to remember to bring my notebook home on Monday. I've got my jet and rod sizes written down in there. I've got a wide band fuel air meter and I found that the richer I went, the faster I went. I started out averaging about 13 to 1 and I think I was at about 12.6 to 1 on my last run. By the way, I'll have that meter with me at Clay City if anybody wants to check their Fuel-air ratio we can hook it up. You've got to install a bung in your exhaust in order to do that though. I think it's the same bung that's used for a typical O2 sensor on most new cars so they're readily available. I'll find out the size Monday and post it here.

 

[Garbageman]

I did get rid of the bogging problem last seaston. I switched from a stock fuel pump to a carter street/strip pump, problem solved. Really. Jim saw me run one pass last year were the car bogged but that was driver error, not enough rpm. Really.
Ray the AFBs work fine
Yes the AVSs work better
But where's the challenge? If it was easy everyone would do it.
Good luck. I'll keep you posted on my tunning efforts.

 

[Ronnie Russell]

The AVS is an old design. Late 60s, I believe. Chrysler products. Adjustable secondary air valve and 3 step metering rods. The best damn AFB ever made. Dont know why Carter dropped it. Must have been financial. Bring it back 30 years later and call it "revolutionary improvement". Not sure if the new ones have the 3 step rods, but I hope so. Has to help fuel economy, especially in a single carb. set-up. But as Paul said, AFB works fine, AVS works better. Ive never had bog with the AFBs but the adjustable sec. air valve is nice to have in case one has that problem. Jim justs likes having the best. bang

 

[dq409]

Jim justs likes having the best. bang

Partly true,,, but as Garbageman said, it is the launch rpm that causes/cures the bog.
Each engine and combo will create different problems. For some reason this engine of mine loves to suck the secondaries wide open from the gitgo.
If I launched it at the prefect RPM there was not a problem but a slight drop in RPM it would bog.
In using the brake launch method it was really hard to hold the car back and achieve the required RPM. I tried everthing to get the AFB`s to react slower but could never get them right.
Now with the AVS carbs it`s not a problem at any RPM launch. I can adjust the secondaries as tight or loose as need be.
If there is a better designed performance part availible for a resonable upgrade price why not get it???

Isn`t this what we all want? Adjustability ? Ease in tuning?

I went from a 12.99 et to 12.3 after changing the carbs.
In my opinion the AVs carbs are better all the way around.
From talking to the Edelbrock reps at the races they say that the AVS has a better fuel metering/delivery design then the AFB`s.

I for one won`t go back to the AFB`s,, ,,dq

 

[models916]

Big Squirt

You can by bigger squiters for the AFB. Tune the secondary opening with weights on the top flaps. It's just counter ballanced. Add weight=slower opening. Still, a bog is a lean spot, cure it with fuel. If the engine is pulling the secondarys open it wants air, just give it a richer shot.

 

[dq409]

You can by bigger squiters for the AFB. Tune the secondary opening with weights on the top flaps. It's just counter ballanced. Add weight=slower opening. Still, a bog is a lean spot, cure it with fuel. If the engine is pulling the secondarys open it wants air, just give it a richer shot.

True but false,,,, Try adding or removing weight at the track. not that easy or fast.
A small wrench and screw driver and literally a few seconds and the AVS is re-tuned.

You are some what right and wrong on the bog. If your secondaries open too soon it will bog big time.
I`m not saying that the AFB`s are a bad carb what I am saying is that the AVS`s are better when it comes to tuning in the secondary flaps.
With the design of the AVS all the tuning is done with the tension spring screw . no guessing on how much weight to add or subtract. What do you use for weights? how to keep it in place? Drop them down the carb !!!
Pain in the a** if you ask me !!

Why not up grade if and when you change carbs?
Why not go for something that looks the same but is a better design?
Seems to be a no brainer !!!

 

[Ronnie Russell]

dq, "seems to be a no-brainer". Money!!!!!!! There are a few of us of this web-site that have to pinch pennies. As I said, the AVS is better, but I can make the AFB work just fine. And besides , You need adjustable sec. air valve to tune often because of those "paint buckets " you are using for secondary jets!!!!!!!! I know,,, e.t. slips dont lie. Cannot argue with you there, but with .104s, that air valve better kick open REAL quick.

 

[dq409]

You need adjustable sec. air valve to tune often because of those "paint buckets " you are using for secondary jets!!!!!!!!

You can talk penny pinching because thats where I`m at most of the time.
I did say when you are changing carbs or in my case having a bog problem that these carbs will help cure.

I bought the AVs`s then sold the AFB`s at a swap meet and did fairly well on them.


On to jet sizes,,,, Like i said I increased sizes one to two steps at a time to get where I am.

NOW,,, what are you other guys using ??? Are mine that far out there that I`m gonna get a razberry over them???

 

[SS425HP]

Jet sizes

Jim, nobody is going to Razz you over a couple of sewer drains!!!!!!!!!!!!! Don't you have any vacuum? The fuel just has to fall out to get there? Ronnie, did you have fire hoses that big????????????????? How much fuel do you use on a pass?????????


















































Just kidding, Jim

 

[jim_ss409]

The last time I was at the track it was a cool day and my fuel air mixture was a bit lean. So I started jeting up. I didn't have two sets of every size so my carbs are different front and rear. I should also add that I was running the 94 octane pump gas that we get around here. It has some ethanol in it so it would require slightly larger jets anyways. Also my manifold is modified in a way that would be like an open carb spacer, that usually requires slightly more jetting too. Anyways,,, Here's what I ended up with on a pair of 500cfm Edelbrocks...
Front carb... Primarys... 389 jets with 6347 rods Secondarys... 400 jets

Rear carb... Primarys... 383 jets with 5749 rods Secondarys... 398 jets

When I left the line or shifted the fuel-air meter showed the engine ran a bit lean (about 13.5) for a second or so then level off at about 12.8. after installing the larger rear jets the fuel-air stayed much flatter and ran at about 12.5

By the way I'll bring the fuel-air meter with me to Clay City so if anybody's ambitious enough to weld a bung into one of the header collectors we can hook it up while you make a run down the track. Apparently the thread size is M18 x 1.5 It's suposed to be a comon size and easy to find at most parts stores. Here's one on line... http://www.innovatemotorsports.com/xcart/customer/home.php?cat=251

 

[MRHP]

Jim, what tire dia. and rear ratio you using. If I recall we have similar engines. I am looking to put in 4:56 gears for Clay City. Too low? I have a t 10 4 speed and 3:36 gears right now.

 

[jim_ss409]

I've got 4.11's and my tires are just a little over 26" tall so I was crossing the line at a little over 5,900rpm on my best run of 112mph. Here's a link to a really good calculator. http://www.race-cars.net/calculators/rpm_calculator.html It's interesting to see how much different tire sizes can affect your rpm.