Hello everyone, getting in to the last stages of a build of a Cadillac 4.5 V8. Looking for opinions/experience when it comes to fasteners for the exhaust manifolds. From the factory, it used a mixture of studs and bolts. Would like to use all studs in the reinstall. Any guidance for what I want to buy and where I should source them? Assuming grade 8 hardware. Lock washers/lock nuts recommended in this application to prevent loosening? Any other tips, vendor suggestions?
Threads are M8x1.25
Thanks so much,
Anthony
Typically exhaust manifold bolts are not grade 8. They do need some ability to stretch as they heat and cool. Don't have any ideas where to get them for that engine. Maybe a search with the tread size will turn up something? Since its metric there has to be a lot of cars that use something similar. Maybe you can find some Honda performance suds or something similar?
Agree with TJ, use grade 5 for the exhaust.
ARP and other manufacturers make High Quality Locking Exhaust Fasteners in Standard and Metric Thread Configurations. Most American Auto Manufacturers switched over to Metric years ago. Some GM/Ford uses mixed, making it even more Fun! Easily sourced.....
Good Luck,
Bobby
Hello smokus,
When using Metric fasteners, don't forget that the tensile strength is designated by Class, not Grade. There are several Metric Classes. A Metric Class 8.8 fastener is approximately the same tensile strength as an SAE Grade 5 fastener. A Metric Class 10.9 is about an SAE Grade 8.
The shop manual covering your engine may call out the specification for the exhaust manifold fasteners. Unless you have done some considerable modifications (headers, ported heads, etc.), the stock grade fasteners should suffice.
Respectfully submitted,
Christopher Winter
Thank you everyone for your input. Hadn't given thought to the need to be somewhat "stretchy", but it makes sense that you don't need incredible raw strength there, and the brittleness that comes along with that strength is not desirable given the life they'll live. I guess that was why I couldn't find grade 8/equivalent hardware for this purpose.
It seems like ARP is a one stop shop for this. After checking out their website, looks like they have a lot of offerings in that thread size, locknuts, etc. Almost everything seems like its made out of stainless steel though. Forgive me here if I'm wrong here, but isn't stainless "brittle" to some extent? As in, not the material you would want in this application?
I know, seems like a lot of effort for a minute thing. I just hate a ticking exhaust manifold (almost as much as I hate breaking a bolt on a 45 degree angle, inches from the frame). With the engine on a stand, now seems like the time to do it once (hence I am considering spending 100+ dollars on ARP hardware ;D)
Thanks guys,
Anthony