fuel pressure
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Thread: fuel pressure

  1. #1

    fuel pressure

    Im sure this has been covered, however, im running usual 355 build, air gap, comp thumper, 750, headers etc, was going to run electric fuel pump. What kind of pressure do i need and is it mandatory to run a regulator. I see holley carries one that doent require one. Thoughts/ experience o n the matter?... thanks

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  3. #2
    Administrator 1946Austin's Avatar
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    Most carbs are very sensitive to higher fuel pressure, so I always run a regulator and a pressure gauge, even if I run a mechanical fuel pump!
    I've seen mechanical pumps put out 8-9 lbs. of pressure, and that's way too much for most carbs to stop. I set my pressure at 5 lbs. and some say 6 lbs. is still fine. I just like a little margin, and at 5 lbs. it never has delivery issues or flooding either.
    A friend had his 350 with a stock fuel pump flood out on the way home a couple years ago. He went and bought a new carburetor, and it still flooded. I told him to put a gauge on it and the stock pump was putting out 9 psi!! We installed a regulator and no more issues.
    Vall

  4. #3
    thanks...will be checking into that for sure. That being said, the ads speak of how many gallons per hr. I am assuming that high volume isnt necessary for basically a small build. yes?

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    Senior Member sbauman2's Avatar
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    Here's my

    2 cents. My 53 has the +.030 428, a cam with lots of lift and duration, big port heads, 2 650 Holley double pumpers on a tunnel wedge manifold, 3/8" fuel llne and a single Holley electric red pump. It has 4-5 psi at an idle, drops to 3-4 when I rev it and when driving and I nail it the motor just continues to pull and never feels like it's starving for fuel. My Willys has a 283, 202 heads, a cam with lots of lift and duration, Edelbrock single carb tunnel ram with a Holley 650 double pumper, 5/16" fuel line and also has the Holley red electric pump with no regulator. It has 5-6 psi at an idle and drops to 4-5 when I rev it and definitely doesn't feel like it's running out of fuel while driving it and nailing it. The 53 has a fuel block mounted on the firewall with a fuel pressure gauge and the Willys has a fuel pressure gauge in line right before the dual feed hard line to the carb.
    Have you given any thought to going into your settings and entering your name for your posts? You can still use 'chopper warehouse' as your avatar if you want to keep it. We just seem to like first names around here; makes it a bit more personal.
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  7. #5
    Administrator 1946Austin's Avatar
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    I ran the stock mechanical pump on my Falcon with two 1850 600 cfm Holley carbs, 3/8" fuel line, a really big cam, with Edelbrock heads and it never had fuel starvation. It would be tough to not get enough gas with almost any street driven setup.
    Vall

  8. #6
    Senior Member manicmechanic's Avatar
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    Agreed. What HP engines need with carbs is not pressure but volume.
    Hidden Content I have no extra cigarettes, money, beer or pot. But I do have extra bullits. Scott

  9. #7
    Senior Member Road Angels's Avatar
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    Think smooth flow and consistent flow... things like fuel regulators and dampeners work wonders on drive-ablity...even high pressure systems use them from the factory.. since every one is bragging about the engines...all I can say is I am running 90psi....on a loop system ...ooopps that is at the injectors...lol...I am with Vall on the reg and a gauge...the gauge if its a good one can help you spot fuel problems
    Lash

  10. #8
    Senior Member mmhotrod's Avatar
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    Quote Originally Posted by chopperwarehouse View Post
    thanks...will be checking into that for sure. That being said, the ads speak of how many gallons per hr. I am assuming that high volume isnt necessary for basically a small build. yes?
    If you buy a Mallory pump with vacuum regulator you can adjust for 3-5lbs for driving and when you whack the pedal the vacuum loss let’s the pressure go up to 9lbs or whatever you wish so you never starve. I paid 300 for a 140 gpm return style setup which is supposed to run a cooler pump motor because of less resistance in the line. I have never had a problem yet on both vehicles. 9 years on one and 5 years on another.
    and as everyone else mentioned put an inline gauge in to see the pressures so you can adjust as necessary
    Last edited by mmhotrod; 07-31-2019 at 11:57 PM.
    Mario





    "I post the work on my hotrod, not because it's the best way, rather it was the way I had to get it done with the resources I had.................
    Of which I might be an encouragement to other hotrodders".

  11. #9

    fuel linnnne dia.

    first, thanks for all the help on fuel pressure/ regulator scenario... as it is a complete build, im seeking experience on line sizing for a mechanical pump...1/4..or 3/8 ?.. this setup will be on a driver...355 ,670 avenger, voodoo cam vortec heads...thanks in advance

  12. #10
    Administrator 1946Austin's Avatar
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    I run 3/8" regardless of whether it's a driver or something well built.
    Vall

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