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Howdy all! I'm looking to top off my '69 351W that is almost done getting rebuilt...finally!!! I put in the Edelbrock Performer RPM cam and aluminum heads...I also plan to use the EB Perf RPM alum intake (i want the RPM airgap but i'm concerned about clearance issues with my stock Mach 1 hood) and i was wondering what carb should i use...the 600cfm or the 750cfm? electric choke or manual?

thanx again!
paul
 

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I know that Edelbrock recommends the 750cfm with your combination. But a lot of the articles in the Mustang mags say that it is too big. I guess it depends on the type of driving you intend to do. With the upgrades you have done to your engine, the 750cfm would probably work fine. I prefer electric chokes.
 

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I personally for street use wont use a 750 on anything smaller than a 429

In my experience, holleys hit MUCH harder than edelbrocks, too

Ask around about which brand of carb vic edelbrock himself used on some of his cars...

Holley!
 

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Go with 600CFM, I had 750 in mine and it did lose torque.
I have Edl RPM Performer and World Windsor ported heads
and radical Crane cam and 600 performed better on my engine.
(definitely on 1/4 m)
 

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How about a Road Demon 625cfm? I have seen them in a lot of engine build-up articles but they were really cutting them down on a Cobra forum I was reading. They all recommended Holley or Edelbrock over them. Anyone dealt with a Demon carb?
 

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I have demons I love them. I had a 625cfm on my 351C I have a 750 speed demon on the 429 now.
I have the Road Demon on the shelf if your interested.
When you know how to tune them it really goes.
 

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This is a formula for estimating the needs of the motor:

rpm x disp / 3456 x .085 = cfm

Or, something like 6000 x 351 / 3456 x .085 = 517.9 cfm

This would be a 351 cid motor with peak rpm of 6000 and a volumetric efficiency of 85%. Obviously, some motors are built to rev higher and have a higher VE. So adjust the equation to suit your particular setup.

I prefer the Edelbrock for the street. I'm well aware that Chrissy Edelbrock runs a Holley in her race prepped Shelby. But I don't drive a race car. For the street an Edelbrock will keep up with a Holley just fine.
 

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290°
300°
224°
234°
0.496''
0.520''
107° / 117°

Correct cam profile?

Engine compression ratio?

Transmission type and rear end gear please...if auto, include converter size and/or stall speed.

Prospective use?

Get back to us....
 

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The air gap is the same height as the RPM manifold. I'm running the same motor as you w/ same setup. I'm running Edelbrock 750cfm carb. I used the Edelbrock parts list to make 411 h.p., they recommended 750cfm carb. Mine runs very well.
Pete
 
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