Holley Power Valve Question
Thread Starter
Melting Slicks
Joined: Jan 2003
Posts: 2,713
Likes: 31
From: Shreveport LA
LA Events Coordinator
Holley Power Valve Question
I have a Street Avenger 670 and want to change the power valve. What is the difference between:
Single Stage Power Valves?
2 state Power Valves?
High Flow Power Valves?
Single Stage Power Valves?
2 state Power Valves?
High Flow Power Valves?
Pro
Joined: Jun 2004
Posts: 700
Likes: 0
From: Lantana TX
Single is activated at a predetermined Vac level 1.5-2 " below your lowest vac # in drive (auto) or in gear for a stick.
2 stage is exactly the same but it help with a first enrichment stage at a high manifold vac level....developed for ex. tow truck pulling somone that needs more fuel but can't wait for the Vac to drop to get get it
High flow is I believe the standard today and I think it is also called a picture window PV. They used to make other PV with circle holes instead of the picture window, but as usual things change.
That being said pic a standard holley PV and use that. I do not think they are even making the 4or 6 hole PV's any more.
Why do you want to change the PV?
Last edited by 76 sting; Dec 7, 2008 at 12:58 PM. Reason: add line
Melting Slicks
Joined: May 2002
Posts: 2,716
Likes: 121
From: Sulphur LA
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
single stage is what comes in most holleys, the two stage is as described above, I think that the carb has to be designed for the two stage to use it, the high flow PV is for engines that need more flow from the PV circut beyound what is normal. The high flow PV has more clearance between the internal stem and the houding to allow more flow through the PV, a standard PV (single stage) will flow enough fuel to support a .120" orffice. most holleys have a PV orffice in the .060 to .070" size. The L88 vettes had a holley that had .092" PVCR's if I rmember right and used the single stage PV's. The internal main well will not out flow a regular PV, the limit will be the main well.
Why do you need to change the PV?
Neal
Why do you need to change the PV?
Neal
Thread Starter
Melting Slicks
Joined: Jan 2003
Posts: 2,713
Likes: 31
From: Shreveport LA
LA Events Coordinator
Pro
Joined: Jun 2004
Posts: 700
Likes: 0
From: Lantana TX
I bought a Holley book used of of e-bay for $8 and that was the best bargin that I ever got. You really need to farmiliarize youself more with the circuits, i.e. idle cruise, and WOT.
what type of idle issues are you seeing? we need details...
Melting Slicks
Joined: Feb 2006
Posts: 3,428
Likes: 5
From: Japan
Check the accelerator pump lever on the primary bowl to make sure it's adjusted properly. It should be adjusted so that at WOT it can still move at least an additional .015", and at idle it should be just slightly off the pump cam lever (.002" or so) so that fuel isn't dribbling out of the boosters at idle. As long as the PV isn't blown and it's rated at 1.5 inches less than idle vacuum there shouldn't be a problem there. As for the main jets, they don't affect idle, so if you have an overrich idle condition changing the mains won't affect the problem.
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