Thread: Why would my PCV be buzzing?

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wrong one for the amount of vacuum your pulling, had the same problem on a crate motor. went through about 4-5 before i got he correct one...joe

How do you tell if one is good or not??

Originally Posted by DennyW

Absolutely. They are different although they may look a like.

Remember also, just because one rattles, doesn't mean it's good.

Are they ID'd for vacuum level by the letter seen on the piston?

I pulled a 455 Buick valve and replaced it with an SBC valve since I required a 90 degree turn for the hose.
The Buick piston was marked with the letter "A".
The SBC was "E" or "F", not sure there.

I asked about vacuum levels, but that was a new one on the parts guy.
I settled for a generic brand and it's working well.
Better than the original Buick methinks.

The generic SBC valve probably doing ok due to the mild cam in the big Buick engine.

I took a look at a 400-M Ford Cleveland valve, but saw no markings inside.