Club Cobra - intake/carb ?

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I was talking to a race friend of mine and he stated that if my Intake has teh divider between it I will need more carb than if it doesnt...does this sound right?

Looking to buy a new carb for my 427 S/O Mild cam, Ross Pistons. Your typical Build ..what are most guys using Carb wise. My friend also did alot of dyno tests with various carbs and stated that the Hollys had significantly more HP. Thoughts?
also what kind of jetting are some of you using ..Im in Calgary which is at around 4300 FT
My Carb issues have drivin me nuts so time to go new. Thanks for any input

Need some answers first

Scufty What size is the motor? Is there any head work done? What exhaust are you running? Specs on camshaft? Compression of motor. Max rpms you think the motor will turn? Solid or hydro lifters in the motor? With out these answers, you have way too much area to quess at. A single plane mainfold will give you more power at 6,000 rpms than a dual plane. You can run a 600 vacuum holley on this motor up to a 950. Stab in the dark for be a 780 vacuum holley with a edelbrock performer manifold. The ports on both the heads and intake will need to be gasket matched for more power. Rick L. PS for the jetting you will need to go either to a dyno shop and have them set up the car withthe motor in it, or go out and buy an LM-1 AF meter for the car and set it up that way. You will need a bung in either the side pipe or the exhaust pipe about 6-12" after the collector location. you will be looking for about 12.7 - 13.2 a/f for max HP and torque.

There is a lot of info on this, but the simple explanation is that with a divided plenum 180 intake there are only two venturies to feed each cylinder. On an open plenum intake 360 intake, there are all four venturies available to feed each cylinder on each intake stroke.

So, you can use a smaller carb on a 360 intake. However a 360 intake also reguires bigger jets to maintain the same fuel/air ratio.

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Take your intake down to a machinist and have the divider machined down about 3/4" or so or do it yourself. This will allow your fuel mixture to flow a little better with a 750 hp double pumper. Just a thought and when my machinist did mine I noticed a big difference. I also noticed a big difference when I went to a big 3/8" fuel log (I don't know why but my car immediately became a lot more responsive). I am running a 427 med riser with a fairly healthy cam and some pretty good bottom end work as well.

Clois

Quote:

Originally Posted by Clois Harlan (Post 926790)

ditto on that.....when I built my 351-W for my fastback in the early 90's I used a dual plane Performer mainfold. a few years later I saw Edlebrock came out with the same basic maniold, but had the divider cut down about 1/2 to 3/4 inch..... they claimed at the time, it would equalize the airflow in the intake and make for better and more even performance across the rpm range...

One cold winter day I pulled my intake and went to a buddies shop that had a mill and we cut down the divider by about 3/4 inch, seems my car ran a lot smoother/better at low rpms, couldn't really tell any difference on the top end of the rpm range, but I'm sure it was better........

David

Thanks all...Yes I did exactly that on my intake for my 289 in my mustang ...just curious as to how that affects the carb....good answers thanks