Exhaust manifold bolts

[Ridgeline]

Can someone out there tell me what size bolts I need to put a set of stock exhaust manifolds back on my 403 olds? It has headers. Will the header bolts work? Thanks in advance.

 

[Blake442]

The header bolts will be too short, but you can use them to compare the threads and just get some longer ones from the hardware store.

 

[pontiacgp]

and when you install them butter them up good with some anti-seize

 

[RITTER]

should be 3/8" course thread

 

[pontiacgp]

and I'd be using at least a grade 7 bolt...

 

[RITTER]

Well, I have never heard of a grade 7 bolt but I would just use Grade 8 standard. Your local NAPA store should have a bolt bin yopu can get these from. Although, running exhaust manifolds gives you the option to run studs so I would get atleast a couple for each side to make things easier.

 

[pontiacgp]

Grade 7
133,000 psi
Med. Carbon
Alloy Steel

just a bit softer then a grade 8 easier to drill out if needed

 

[RITTER]

Grade 7
133,000 psi
Med. Carbon
Alloy Steel

just a bit softer then a grade 8 easier to drill out if needed

hmmm, good to know 😛