power valves

diegokid · #1 (**permalink**) 07-24-2010, 06:32 AM

Why is running a Holley DP square with two powervalves considered not desirable for street use? I have ran them with the secondaries plugged and with PV in both. Some ran better with powervalves in the secondaries some didn't. Is there any reason to do this or not to do this for a street carb.

pusherfans · #2 (**permalink**) 08-10-2010, 03:48 AM

I have tried a power valve on the secondary side and no power valve and made up for it by increasing the jet sizes there up 6 and the end result was identical, so I don't get it either.

vector1 · #3 (**permalink**) 08-10-2010, 04:21 AM

primary and secondary power valve allow leaner part throttle operation for street use, better mpg. i don't see a down side. road race carbs usually use this also, i have 2 bg's and a justus carb with secondary pv's. there is the chance of uncovering the secondary pv on acceleration and going lean, maybe this is why it is considered undesireable by some.