Some More Holley Power Valve Questions

[billysboat]

Ive read almost every post on Holley power valves. It seems they create quite a havoc on motors.
I am going to change mine...well because, it's cheap enough to be sure it is not bad and if it was bad, I should know right away.
Answers to the questions I am about to ask may help me and others understand better and diagnose a power valve issue.

If a newer Holley has check ball protection, Does this work? Or, will or can it still blow?

Why do marine applications use the 2.5 power valve?

Is it always better to do the vacuum test on the motor itself and use the power valve 2 points lower? If yes, then why?

Doe anyone have a list of all of the issues a power valve can cause?

Are there any more power valve questions I forgot to ask?

 

[jtmarten]

Re: Some More Holley Power Valve Questions

Your best bet would be to ask Holley Tech Support. They're very good and respond quickly.

 

[mkast]

Re: Some More Holley Power Valve Questions

http://www.holley.com/TechService/

 

[rad1026]

Re: Some More Holley Power Valve Questions

Is it always better to do the vacuum test on the motor itself and use the power valve 2 points lower? If yes, then why?

Yes. Power valves dump a significant amount of fuel in to the carb when they open, like rejetting the carb about 10 x higher. If the PV opens too early you will create a huge rich mixture. If they don't open at all you will never realize the potential of your carb. Given all other things in proper condition, no vacuum leaks, good valve seals, etc. You should set your PV at 2 points lower then your vacuum test results. Altitude has a lot to do with it. Air pressure at 5000 ft is a lot lower then at sea level and that will effect the vacuum characteristics of your engine.

The check ball was designed to protect the PV diaphragm, whether it works or not I don't know. I suspect Holly has enough experience with carbs to know what they are doing.

 

[billysboat]

Re: Some More Holley Power Valve Questions

That makes sense to me now. I had a friend who had a Holley on his truck. We live at sea level on the Chesapeake. We would travel to the mountains in Western Maryland all the time. He always kept spare PV's. Blow them like crazy.

 

[wca_tim]

Re: Some More Holley Power Valve Questions

That makes sense to me now. I had a friend who had a Holley on his truck. We live at sea level on the Chesapeake. We would travel to the mountains in Western Maryland all the time. He always kept spare PV's. Blow them like crazy.

Should NOT be blowing power valves on newer holley carb that's set up right!

 

[zbnutcase]

Re: Some More Holley Power Valve Questions

Power valves only fail if engine backfires and the check valve is very effective at preventing it. So if they are "blowing like crazy" there are other issues, don't blame the P/V.

 

[billysboat]

Re: Some More Holley Power Valve Questions

Power valves only fail if engine backfires and the check valve is very effective at preventing it. So if they are "blowing like crazy" there are other issues, don't blame the P/V.

I should have mentioned, that this was long ago probably before the check ball thing.