Dual quads vs. single four.

[Fathead Racing]

I am on the threshold of of yet another 409 build. My goals are a 12 sec. street car. I belive that a single four manifold and carb will perform better on the street. Am I wrong? Has anyone gone from a single four to dual quads with out changing anything else? What were the results? How did it change the way it behaved on the street? ET.? Gas milage? What do you guys think? Should I go with the single four or shoot for the dual quad? For now I am going to place the 690 heads on my 9.5 comp. truck block, stock stroke .030 over 409. Cam will be solid roller 230/240 @ .050. .569/.570 lift.

 

[MRHP]

Well, lets see. For the visual impact, a dual quad is second to only an Algon unit. For performance the single four is the way to go. If I remember correct, the open plenum single is the better of the bunch. I believe the low rpm range( under 3200 ) would be much crisper with a single carb. Now if you spring for an aftermarket intake, one of Rich's, then I would have to change my mind. I assume we are talking stock intakes. The single four also has better fuel distribution cylinder to cylinder. Are you building a stock stroke motor? If you are building a big inch, an aftermarket intake would be the nuts. May suffer slightly on the low side but hold on whe it gets there. I wish I had bigger headers and an aftermarket intake on my 474. Right now it snarls but I am sure there is more bottled up. I run dual 600 Edelbrocks on a stock intake and it isn't bad, but I am sure a 950 Dominator would spruce up the low speed response. Just my opinion.

 

[Ronnie Russell]

Ray, MRHP is correct , even though I hate to admit it. The single is the best for ultimate performance for the street, but doggonit, to me a 409 just aint a 409 without the 2-4s. Im sure you could get close in performance by using 500cfm Carter or Edelbrocks and think of the difference you would get everytime you opened the hood , The 2-4s just seem to leap out. Ever since I sold my share of our Nova to my partner, the car has had a single Holley on it. Runs great but it looks puny without 2-4s. Give it plenty of thought, cause Even though I know you like your trips down the strip, that plays a small role in the over all picture. Either way its those 690s that will make all the difference.

 

[Tony Salins]

Back when I raced my 62 I first ran it with the due quads. I used 750 comp series AFBs. The cam was a Crowler soil lifter cam with specs very close to the Z-11 cam. My best time was a 12.60 but I never could back that time up. The car ran 12.90 consistently. Anyway I thought I'd try a single 4 barral. I used the 400hp stock manifold with a 900 cfm Holley "3 barrel" on it. The car ran the same! Ray that was back in the 70s hope it helps.

Tony

 

[SS425HP]

1 or 2 carbs

Ray, the dual Quads can be set up with progressive linkage, just like your tri carb. I have mine set that way. Even for Racing, it works. I have the stock carbs. It basically idles on the rear carb, and runs down the highway on the rear carb. Not sure where the front starts coming in, but has to be after half throttle on the rear. Plenty of carb to do any street running. Now, put your foot in it, and you have all 8 barrels open to GO FAST. The single 4 is not far behind in performance, but the dual 4s are neat looking. And they will produce more power. Seems to me the fuel distribution has to be better. It will basically come down to "what do you want"? More a preference thing than anything else.

Fred

 

[TomO]

Fat - If I remember correctly.....Travis Horton is running a single 4 on his 409 and turning 10s. I know that Tony Shaffer did some work on the manifold. Maybe a quick PM to Travis would help to answer your question. Heck, give Tony a call.

I truly wish that there was a good single 4 made for the 690 and 817 heads.

TomO

 

[Skip FIx]

I had always heard the 409 single 4 couldn't feed a stroker motor for air flow but the dual quad would. The runners don't look alot different in size though.I think with the carb nearer the ports on the dual quad it would have better fuel distribution.

In the 70s I never got mine to the track with teh single 812 Holley DP I had on it. Dual Holley 715s sideways all 8 opening was how I drove it on the street. But then gas was 0.26/9 for 100 octane premium. Best time at Dallas International Motor Speedway was 12.20s @108.,headers big F Nitro 310/320 .580/.590 Crane cam.

 

[Nine iron]

Mickey Thompson manifolds

Does any one no much about the MickeyThompson cross ram? How many were made and how many out and about now? Never see them for sale any where including ebay. Hot Rod Chevy shop here in Oregon told my son they never made such a beast for a 409. but I know they did. What would a guy expect to pay if he found one?

 

[wrench]

MT Crosram

Does any one no much about the MickeyThompson cross ram? How many were made and how many out and about now? Never see them for sale any where including ebay. Hot Rod Chevy shop here in Oregon told my son they never made such a beast for a 409. but I know they did. What would a guy expect to pay if he found one?

They come up for sale on ebay occasionally......and fetch a hefty price.

I remember someone posting on CT a while back that he bought one in a little store that was using it as a planter in a store window. How gauche....

Here's a link to some pictures on my site

http://wrench.vox.org/modules.php?s...ame=Gallery&file=index&include=view_photo.php

And a pic from the site:

 

[JimKwiatkowski]

Does any one no much about the MickeyThompson cross ram? How many were made and how many out and about now? Never see them for sale any where including ebay. Hot Rod Chevy shop here in Oregon told my son they never made such a beast for a 409. but I know they did. What would a guy expect to pay if he found one?

Nine Iron,Here's a photo of my Cross Ram,not many were made and they can go as high as $2,000 on ebay

Wrench,it looks like the cross ram you posted has the ears cut to fit low performance heads

 

[No409]

my motor dynoed 585hp with a 850dp, and a 4bbl intake. it ran 10.70`s in a 3600lb car(w/driver)

i got one of Riches intakes and im gonna go the 2x4 setup. hopefully a little more hp.

 

[wrench]

intake

Wrench,it looks like the cross ram you posted has the ears cut to fit low performance heads

By golly, you're right! I never noticed it before. Good catch!

Thanks,

 

[Skip FIx]

Was that a factory 4bbl intake making 585 hp? Or one of Lamar's?

 

[No409]

yep, 63 4bbl intake , heavily ported, with a 1" spacer. I think all the power is in the heads. these things are sick. 690`s heavily ported, with the center 2 exhaust ports raised to the same height as the outter 2. had to have my hooker supercomps cut and new tubes made on center 2. should be up and running real soon( my race car is broken also, so money is going into that also)

 

[Skip FIx]

Plenum divider cut down/out?

 

[tripowerguy]

Ray do you remember Terry Prince at the convention? He was a former owner of one of the Z-11's at the convention, the red one. We talked about racing at Pomona and he ran a 60 with a 348 hi pro with single 4 barrel. This was stock Chevrolet same as a 350 hp but with 4 barrel, don't remember the hp rating. Anyway I have a 1961 Dragnews that shows him winning A stock with 104 mph and 13.18 et, this is on bias ply tires. So your heads should flow better than those heads and with that cam I would think you would be somewhere at110mph and mid to low 12's. You also have a better manifold than that one, I would think a Holley would make a little more top end HP but Terry ran an AFB I believe. Roy

 

[JimKwiatkowski]

Roy,are you sure that was a 348 and not a 409 13.18 is a very good time for a 348.Ray has a 409 shortblock and he's running 13.60's

 

[tripowerguy]

It was a 348 probably bored .060 over as that was the maximum allowed. I talked to him at the convention and he said he was building another car just like it. I don't know why our cars are not as fast but we seem to be fighting a demon trying to match the times of old. Maybe the cam engineering from Chevrolet wasn't so bad. I think about my old 348 315hp which had small valves and three speed, 456 gears, 8:00x14 bias ply street tires. It was 100% stock Chevrolet except it had been balanced and the clearences were on the loose side and it went 13.90 with 101 to 102 every weekend. My cousin bought Wily Cosey's 59 chev which had a 4 speed, 456 gears and wrinkle wall slicks. It was a 348 .040 over Engle solid lifter cam and a factory hi pro 4 barrel manifold with a AFB. It went the best of 13:06 with 104 mph. Nicholson went in the high 12's and 109 with the first 409 at the Winter Nationals in 1961. That was with a single 4 barrel I believe, that is a long time to rely on memory. The headers are supposed to be so much better now but I ran Hedmon headers much like block huggers of today but there were 4 dump tubes 2 cyl. per tube. Look at times Hayden Proffit turned 119 and in the 11's without todays tires or cam technology. The 350hp 348's were protesting Nicholson because they had to run SS against him at the Winter Nationals. Some of them were going 105 and 13 flat, this is 1961 and we can't seem to match the times now and I'm wondering why, is it the compression, the gasoline or what? We are now running strokers and struggling to match Hayden's time 1962. Roy

 

[CDNpontiac409guy]

Wasn't Hayden Proffitt's car an aluminum front end ?

That record WILL be broken... BADLY, with an all steel car

 

[Fathead Racing]

Carter carb.

I just scored on Ebay a nice Carter Competition series 600 cfm carb. This will be the primary carb on my dual quad setup. Does Carter make a 600 cfm secondary carb with no idle circut or do I have to use another primary type carb??

http://cgi.ebay.com/ebaymotors/ws/e...d=1,1&item=7990600482&sspagename=STRK:MEWA:IT

This is the dual quad intake that I bought.

http://cgi.ebay.com/ebaymotors/ws/e...d=1,1&item=7989608139&sspagename=STRK:MEWA:IT