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Old 03-21-2010, 07:56 PM
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carb/lines size/pressure : what's right?

Hi; just looking for help/recommendations; 69 camaro/383 sbc/forged/rollercam build (app.450hp), 750 holley dp, 3/8" single fuel line; what is a quality mech.fuel pump to use without any bypasses or regulators; barry grant offers one that puts out 9psi; is that to high? and what inline fuel filter before carb. with cleanable mesh filter? thanks Johns

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Old 03-21-2010, 08:21 PM
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9psi is border line too high and more than you need. Less fuel pressure is better.
You want flow volume "GPH", not pressure. A 6-7psi fuel presssure is better ( holley carb) 5-5.5psi edlelbrock, carter, or Qjet.

The 3/8" in /out paper element type inline fuel filters work better.

A 450hp engine needs 45GPH at WOT max power output.

Most fuel pumps are rated GPH @free flow, not while flowing thru the fuel system.
This can be deceiving.

Short of flowing the whole fuel system on the motor/in the car at rpm a rough rule of thumb is to divide the free flow GPH rating of the fuel pump by .23 to get a rough idlea of how much engine horsepower it will support.

This assumes all the fuel lines, fittings, filters, joints, hoses and tank pick up tube are not under sized. Avoid right angle fittings. Avoid excessive heat especially in the feed/suction side of the mech fuel pump.
Mechanical fuel pumps work best if the feed side fuel line is oversized and kept cool. The pump cannot move hot bubbley fuel. Don't overlook the fuel pick up tube in the fuel tank. these help a lot..

Usually, a "110 GPH" mechanical pump gets the job done.

A billet roller cam core needs a special fuel pump push rod.

Last edited by F-BIRD'88; 03-21-2010 at 08:27 PM.
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