Holley power valve help

[Bearcamp]

I put a stock 650 cfm on my 360 big block and when setting it up back fired quite a bit and took out the power valve. I took it apart and has a number 9 stamped on it. Should I replace it with another 9? The engine is stock with lake style headers. I've heard you should run them and check the vac to determine what valve to install but it's apart now. I'm running an automatic transmission too, in case it matters. I even looked online for a number 9 and found 8.5 and 9.5s but no 9.

 

[Torch]

I'd go lean for a daily driver
and pick the 8.5 or go stock
but I don't run the diaphragm power valves anymore I run the all metal ones and they rarely go bad

No

Yes

Holly Dual stage power valve

 

[bgbrktracer]

Must be older carb without power valve protection. Kit to solve that problem is about 6 bucks at most parts stores. I allways run a 45 or 55 power valve, no bigger that 65. That way you know it won't come in till you need it. I've seen cars with correct jets and float levels running way too rich because of incorrect power valve.

 

[Sumfuncomet]

Holley tech line

Holley help is only a phone call or email away. Go to the source and ask them! Good advice from them.