Gumby22

I’m replacing head gaskets on a 1997 Pontiac Grand Prix, 3.8 (not supercharged). The exhaust manifold hardware - for securing the manifold to the head, not the flange bolts - is not in good enough condition to make it worth the time to clean and reuse (at this point).

The original hardware is 5/16x18x2 and I can’t locate any exhaust stud or bolt kits in that size. I have to have at least 5 studs for securing the heat shields and oil dipstick tube - the rest can be bolts.

I’m not great with search engines, but I’ve tried searching by application, size, and other GM vehicles from that era with 3.1/3.4/3.8 engines and NOTHING is coming up. That’s using google, aftermarket parts websites such as o’reilly and NAPA, and rock auto.

I’ve already checked with the local GM dealer and naturally they show discontinued.

Can anybody provide a source for these or put your superior search engine skills to use on my behalf?

Thank you.

Gumby22

Well if someone happens to find a source for these, by all means post it, but I ended up chasing threads on the old hardware and reusing it. I didn’t have a choice as this job needs to get done and I didn’t have anything to replace them with.

Also, I ended up finding that the studs were 5/16x18 on the end that threads into the cylinder head, but the other end where the nut threads on is M8x1.25 . It’s really annoying and stupid that they’re set up this way, but it also makes sense because this was a time when GM was transitioning to metric bolts and manufacturing was divided between the US and Canada, and possibly a few other countries.

Although I wasn’t originally aware they were set up that way (it’s too easy to ASSume everything is metric these days) my intention was to get a set of exhaust studs that were 5/16x18 and just replace all the hardware with them (as opposed to having a hex bolt with the additional 1/2” long stud on top), unfortunately the closest match was M8x1.25. If you’ve ever compared those sizes, they are nearly identical, with the 1.25 pitch being just a little bit finer than the 18 pitch. Had I known metric would be my only option, I’d of asked the machine shop to re-thread the exhaust bosses for metric bolts.