Holley 4 bbl fuel pressure

[jetmek]

Hi will a stock 8ba fuel pump deliver enough fuel pressure to adequately supply a holley 4 barrel?

[BUBBAS IGNITION]

Should be plenty........1 pint in 15 sec is typical......

[4dFord/SC]

Mine runs fine with stock pump.

[scicala]

Even though it's got a four barrel carb now, the engine can still only pull so much fuel with the flathead V8. Stock fuel pump is plenty.

Sal

[19Fordy]

Yes, to a holley 390.

[Pete F]

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Holley carbs need 7psi to run properly and I don't think a stock pump will push the volume you need to run effectively.
Now if your only going to cruise around town the stock pump will probably work but if your into the throttle hard I would bet you will run out of fuel upstairs.


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[4dFord/SC]

Originally Posted by Pete F

Holley carbs need 7psi to run properly and I don't think a stock pump will push the volume you need to run effectively.
Now if your only going to cruise around town the stock pump will probably work but if your into the throttle hard I would bet you will run out of fuel upstairs.


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I've run mine at 80 on the stock pump without a hiccup.

[scicala]

Originally Posted by Pete F

Holley carbs need 7psi to run properly and I don't think a stock pump will push the volume you need to run effectively.
Now if your only going to cruise around town the stock pump will probably work but if your into the throttle hard I would bet you will run out of fuel upstairs.


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Not true at all. 7 PSI if your running 7000 rpM for an extended period possibly. That high of pressure, and your asking for possible flooding issues. Enough pressure to fill the bowl is enough for a Holley or any carb to run right.

Sal

[Pete F]

[QUOTE=scicala;1517103]Not true at all. 7 PSI if your running 7000 rpM for an extended period possibly. That high of pressure, and your asking for possible flooding issues. Enough pressure to fill the bowl is enough for a Holley or any carb to run right.

Sal
7 psi will not cause flooding on a Holley four barrel it's a totally different needle seat and float set up .
Holley recommends 5-7 psi and 7 at idle
7 psi on a 94 will flood
3 psi and low volume and you will be looking for a lean condition.

[flatjack9]

[QUOTE=Pete F;1517110]

Originally Posted by scicala

Not true at all. 7 PSI if your running 7000 rpM for an extended period possibly. That high of pressure, and your asking for possible flooding issues. Enough pressure to fill the bowl is enough for a Holley or any carb to run right.

Sal
7 psi will not cause flooding on a Holley four barrel it's a totally different needle seat and float set up .
Holley recommends 5-7 psi and 7 at idle
7 psi on a 94 will flood
3 psi and low volume and you will be looking for a lean condition.

I've been running a Holley 390 cfm for over 25 years now with a stock fuel pump on my 276" engine. Runs 75 mph on the highway with no problem and trust me I do not have a lean condition. I've also had the engine up to 5000 rpm with no problem.

[tubman]

I had the same setup as "flatjack9" in my '36 and never had any problems either.

[Pete F]

[QUOTE=flatjack9;1517149]

Originally Posted by Pete F

I've been running a Holley 390 cfm for over 25 years now with a stock fuel pump on my 276" engine. Runs 75 mph on the highway with no problem and trust me I do not have a lean condition. I've also had the engine up to 5000 rpm with no problem.

That's great
I'm not tying to give you a hard time I am only quoting Holley
And for the past 50 years all the engines and Holley carbs I set up run at Holley spec 5-7 psi



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[scicala]

[QUOTE=Pete F;1517110]

Originally Posted by scicala

Not true at all. 7 PSI if your running 7000 rpM for an extended period possibly. That high of pressure, and your asking for possible flooding issues. Enough pressure to fill the bowl is enough for a Holley or any carb to run right.

Sal
7 psi will not cause flooding on a Holley four barrel it's a totally different needle seat and float set up .
Holley recommends 5-7 psi and 7 at idle
7 psi on a 94 will flood
3 psi and low volume and you will be looking for a lean condition.

Pete,

I said 7 PSI COULD cause flooding issues. I am more than familiar with the Holley four barrels and the fuel valves/float systems. 6 PSI is more than enough for any conditions, and 3 PSI will work too. This engine is not going to use 5 times as much fuel because it has a four barrel on it. Say this flathead has 150 HP tops with the four barrell. It needs approx. 75 lbs/hr fuel to run good at 150 HP. If the stock flathead needs 50 lbs/hr fuel for 100 HP, I can't picture the extra 25 lbs/hr. fuel flow requiring all of the extra fuel flow to need 7 PSI.
This is based on my experience doing carburetor flow testing and development work on flow boxes, vehicles and engine dyno's for 16 years.

Sal

[40 Deluxe]

I find the different responses here interesting. On one side we have the theorists, the armchair engineers, and on the other side the "been there, done that" guys. I think I'll go with the "been there, done that" crowd.

[Pete F]

No two engine builders will ever have the same opinion!
No two engines will ever perform the same way on the dyno that's fact.
Years of spinning engines has taught me to be humble because engines will humble you.
Theory is a good base line but the dyno and actual road tests tell the story.
If you want to try a stock pump and the engine surges on top you are probably running out of gas.
If it pulls strong and you can jet it you will probably be fine.
Read the plugs after hard rides and you will know what's going on.
No offense to my colleges everybody is entitled to there opinion.


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