How much fuel pressure for a Holley 650? - Hot Rod Forum : Hotrodders Bulletin Board
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Old 04-24-2011, 01:19 PM
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How much fuel pressure for a Holley 650?

I have a 402 big block in my 57 Chevy. I had to install a Summit Racing mechanical fuel pump that has the adjustable lower housing. I needed that so I could have my fuel lines routed correctly.

The fuel pump says it puts out 5.7-8.0 psi. That is a descent range and there is no adjustment that I know of on the pump. I'm running a 650 Holley double pumper and it seems to run rich at wide open throttle. It almost bogs like it's dumping in to much fuel. I'm not sure if I should start tuning on the carb or get a fuel pressure regulator and make sure the pressure isn't too high. 8.0psi sounds kind of high, not sure if my pump is putting that much out or the lower 5.7psi.

The float levels are set right and the carb doesn't seem to be overflowing with excess fuel.

Thanks for your help!

Joe

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Old 04-24-2011, 01:25 PM
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I would add the regulator if it was me, You only need 5 psi to run that's alot of engine might take alittle more but it shouldn't need 8 psi.JMO
Add the regulator and set the psi at the minimum if it. 5.7 try that or maybe 6 psi and see how it does from there you will probably still have to do some adjusting at the carb air/fuel mix to get everything right. JMO


Cole
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Old 04-24-2011, 02:58 PM
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X2......most street Holleys are way over fuel pressured and blow the needle off the seat. Unless you run around town at 6,000 rpm all the time then 5 psi should work.
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Old 04-24-2011, 05:42 PM
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Thanks for the replies.

I was thinking 8 psi sounded too high. It looks like a new regulator is on my list. Some of the regulators I looked at don't have a gauge that tells how much pressure you have. The $25 units from Holley have a plug that you screw in. I guess one way is the maximum pressure and back the other way is minimum pressure.

Thanks for your time
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