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Username Post: Anybody ever modify their Holley power valve channel restrictors?        (Topic#372503)
"2nd Year" Silver Supporting Member
Posts: 327
Loc: Central Arizona
Reg: 04-10-22
01-30-23 09:42 AM - Post#2853919    

Looking to modify a nice 4150, 4779 750 CFM double pumper I have on the shelf.

The factory jetting is too rich down low, and I can easily change jets to say #63 from the factory #71 primary jets for a nice 14.7:1 cruise mixture.

But, that means when the PV is operating, not enuf fuel will get delivered at full throttle and the engine will run too lean.

Opening up the two PVCR holes on each side of the PV in the metering block should cure this.

A little math needs to be done to figure out the new hole size before I drill, though.

Anybody ever do this?



Super Senior Member
Posts: 6599

Loc: paradise
Reg: 09-05-03
01-31-23 08:39 AM - Post#2853952    
    In response to DHMelton

i will assume you are using an air fuel monitor. you can always replace the metering block if you screw it up. are you sure its the main jets running rich? the idle circuits on holleys are normaly too rich for a street car.

70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails.

Valued Contributor
Posts: 2981
Reg: 08-06-08
01-31-23 09:39 AM - Post#2853955    
    In response to DHMelton

no, no, no. Just get the newer designed Quick fuel/Holley 4 window PV. ps&_...

"2nd Year" Silver Supporting Member
Posts: 327
Loc: Central Arizona
Reg: 04-10-22
01-31-23 08:41 PM - Post#2853979    
    In response to 66cayne

PV has nothing to do with how much fuel flows thru the PV channel restriction. The PVCR is what determines fuel flow, diff PVs just open at diff vac levels.

The quick fuel metering block has provisions for interchangeable PVCR orifices, but I don't want to buy more parts than necessary



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