Racing Fuel Systems

1050 size Holley dominator carb. alcohol fuel. 700 HP BBC 482". Bracket race in big tire door car. High 5 second potential.

Formally Rons Injection toilet. Still have same Rons belt drive mechanical fuel pump. Fuel cell in engine compartment. Fuel line to fuel log for carb with bypass regulator back to cell at back of log. Engine sounds good. Trans and converter have just been rebuilt. Does not run to potential. Have tried more than 1 carb. 4 link suspension. Have gone thru all adjustments. Actually runs the same ET and MPH of former less powerful engine. In process of testing engine for cause.

Questions have come up about if the fuel system could be the problem as far as the pump and adjustment to pressure. It is set now with a bypass jet to allow 3-4# pressure at idle and 10-11# pressure reved up. Holley style bypass 704 regulator with jet in back to control idle pressure, spring in regulator controlling full pressure. Some say pressure could be too high going down track. Is there any reason to think this could be the problem? Other issues will get addressed shortly in the shop but won't be back to the track soon due to harvest on the farm.

have you seen or looked into the Hilborn style bypass that connects to the throttle linkage? closed throttle = open bypass, open throttle = closed bypass?

seems like your current setup has too high fuel pressure at WOT.?

6-7 psi is where most carbs want to be with Alky. I have a 750 SBC 406, with big n/s, I run 6 PSI.

That regulator is also only designed for pressure between 4.5-9. So having it at 10-11, you overloading the spring in the regulator.

I would think 10-11 psi would be over running the n/s and floats making it really rich not to mention its probably aerating the fuel like crazy.

Can you turn the regulator down to 6 or 7, if not, Can you slow the pump down by changing a pulley?

Also, according to the summit catalog, that 704 isn't a bypass/return style regulator.

Yes the regulator is adjustable down. The regulator has been modified to work as a bypass regulator. It worked well on the previous smaller engine both at the high pressure and as a bypass regulator. Just looking for reasons it might not work now. Never did understand how it could work at the 10-11# going down track before, but it did.

It is typical to see hammer like fluctuations, trying to run 10+ psi at wot on a spring loaded diaphram regulator, without a barrel valve. Not knowing the specifics of the dominator, sounds like it's on the rich side of the flame. Getting back closer to 6psi at wot could get things headed in the right direction for you.