Taking It To The Track

mderoy340 said
You really need to read this thread to understand how a power valve operates. Vacuum keeps a power valve closed.
Power Valve Selection: The Definitive Answer
A blown power valve will pull fuel through the vacuum port and make an engine run pig rich at idle.
I run a 9.5 valve in my 340. Cruise vacuum is 14-15, roll the throttle and the power valve opens. This allows you to run a smaller primary jet at cruise. My PVRCs are .064 and 72 jets up front on a Demon 750DP

I scanned that thread last night. I’m going to read it more closely.

I know vacuum holds it shut. Writing about this is harder than talking about it!

So yes, I was confusing a leaking PV with one that just may be open at idle, or whatever vacuum/rpm.

Thanks for the help. I’ll update after some learning and experimenting.