Quote:
Originally Posted by 64speed
I had two Holley techs tell me conflicting information but we finally decided on the fact that the carburetor does need a regulator at the pressure my pump puts out. So I am putting on a regulator and after talking too them for a while I am sending this 750 back and getting a 770 with vacuum secondaries and its actually cheaper.
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If you have more 7.0 psi delivery pressure your problem might have been flooding past the inlet needles. That said you, you didn't mention black smoke, starting issues and fuel overflowing from your vent tubes like a fountain that would result.
Assuming you were running an FI rated pump, do you not have a regulator to step down the delivery pressure to carburetor?
If using an in-tank pump, you'll need a Holley regulator with bypass. They come preset to 7psi for carbureted applications and can be plumbed into your supply and return lines for by pass so you don't overheat the pump. It's your only alternative. You can install them under your hood (more junk showing) or close to your tank with a short bypass if you don't want it under the hood. The longer line ahead of the regulator doesn't really make much difference in the pressure at carb but you can always tweak it if needed, but it amounts to next to nothing.
If you're using an inline pump, you could also swap it out for inline Holley street pump that is also preset for carbureted use and just run it unregulated.
I put in a Carter Competition series mechanical pump and use my electric Holley Street pump on a switch as a pusher. I've only used it when I had a touch of vapor lock in the heat of summer in traffic. A quick flick of the switch forces the vapor out through the carb vents. The mechanical pump keep up just fine on its own.