I'm installing some as&m headers into my '97 and everywhere ive read about this install, you need to get check valve adapters for the AIR system.

I dont understand the need for these - I test fit my existing AIR pipes and they screwed right into the headers. In fact, i even bought one of the two gm check valve adpaters (really i think it is just the AIR pipe off a 95) and it looks like it fits, but it points the checkvalve fitting that the rest of the system hooks up to in the wrong direction!

Can someone explain what im missing here?

 

Did you get single-cat or dual-cat AS&M's? They stopped making the dual-cat headers a long time ago, so if you bought them used, your in for a surprise, when everything under the hood starts melting.

If you got the single-cat headers, the holes for the AIR connections are (approx, not exactly) an M22-1.5 thread. That was only used on the single cat cars. The 96/97 dual cat manifolds had a much smaller thread.... maybe around 5/8".

So its sort of hard to explain why you don't need adapters, unless you're installing the obsolete dual-cat headers.

 

i'm putting in the single cat headers (just got them new from as&m)

Ill go measure the fittings the next chance i get. I was expecting exactly the situation you described, where the threads wouldnt be compatible, however when i test fit my old fittings, they screwed in perfectly.

I guess its possible that my old edelbrock headers needed a similar adaptor (i didnt install them), but the GM diagrams that ive looked at seem to indicate i have a stock AIR setup.

I was able to screw things in this order: AS&M AIR bung -> male-male coupler (one side had wider threads than the other) -> AIR pipe -> checkvalve - > rest of AIR system.