1965 273 A body exhaust manifold to cylinder head bolt size

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prorac1

prorac1

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Looking for hardware store alternatives to exhaust manifold to cylinder head attaching bolts.

Ends are being attached with studs and nuts.

Washers?

What's everyone using?

Thanks. Eric

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I think this was what I just did...
The end holes are studs - 1/4-20 in the head, 1/4-28 on the manifold side, with conical steel washers. Center two are standard 1 1/4" 1/4-20 cap screws with no washers, and the other two are longer 2" or 2 1/4" (?) cap screws with conical steel washers.

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moper said:
I think this was what I just did...
The end holes are studs - 1/4-20 in the head, 1/4-28 on the manifold side, with conical steel washers. Center two are standard 1 1/4" 1/4-20 cap screws with no washers, and the other two are longer 2" or 2 1/4" (?) cap screws with conical steel washers.

View attachment 1715158331
Click to expand...

Thank you very much. Where did you find the conical washers at?

Thanks again. Eric L
 
And what exactly is the purpose of the conical washers?

I love the cap screw idea. That's great! The center two didn't need washers and are holding well with the small heads?

Thanks again. Eric
 
I thought they were 5/16" - 18 coarse thread going into the head...

The studs in the ends should be 5/16" x 1 1/2", 2" length may be a little too long...
 
I know 67 and later are 5/16 . I know 65 model heads are different at intake side, so maybe they are different at exhaust side too. In either case, the end studs go into coolant passages and need sealant applied.
Metals change in size as they heat. Different metals change at different rates/amounts. The conical washers absorb the difference.
 
The car is a 1963

The exhaust manifolds are 1965

The engine is 1983. Lol

I didn't know that they changed the thread size on later engines.
 
krazykuda said:
I thought they were 5/16" - 18 coarse thread going into the head...

The studs in the ends should be 5/16" x 1 1/2", 2" length may be a little too long...
Click to expand...

We already have the 4 studs. So all we need are the bolts and nuts and washers.

thank you everyone for all the information. Eric
 
prorac1 said:
The car is a 1963

The exhaust manifolds are 1965

The engine is 1983. Lol

I didn't know that they changed the thread size on later engines.
Click to expand...
Don't take me wrong but that information would have been nice to know in your original post.
 
toolmanmike said:
Don't take me wrong but that information would have been nice to know in your original post.
Click to expand...

Yeah. Lol. I gotcha.

I didn't realize Chrysler changed the bolt size on later small blocks.

From what I'm finding, Chrysler liked "changing things". Lol
 
If you turn to your friendly local Mopar provider (me), I will send you the conical washers and correct for 1965 bolts!!
 
Cosgig just confirmed that 1966 and 1983 exhaust bolts are the same size. 5/16. Thanks Geoff!
 
Thank you. Cosgig is hooking us up with some manifold bolts from his supply. Thanks again Geoff and everyone else that provided information. Thanks again. Eric
 
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