On my mechanical-secondaries Holley 750 (double pumper)...is there a power valve inside? I thought power valves were strictly a vac-secondary carb thing. I keep reading about carb tuning and the possiblility of a blown PV from backfire, but I've also been told "no need for you to worry about that, since you have mech secondaries". what's the word? ~Mark
The word is yes..In both metering blocks on a dble pumper you will find a PV..usually a 6.5" from the factory. It richens the mixture below 6.5" by aprox. 10 jet sizes. Sometimes there is only one in the front with a larger jet in back...depends on the part number...runs real muddy when the pv blows..but its not all that commen to see them go ..less you've had some good backfires through the carb
