small block exhaust stud size

[slant6billy]

In an effort to help, my friend's wife lost the nuts for the manifolds. I had manifold bolts in my parts collection and possibly the nuts. I have ARP 3/8 nuts for studs, but the bolts are 5/16. Are the factory studs 5/16 into the head and 3/8 outward to the manifolds? I think I've been in this spot before, but can't remember.

?????
thanks

 

[jasperjacko]

I think they are coarse thread in and fine thread out. Not sure if 5/16 or 3/8 though.

 

[bremereric]

They are 5/16" coarse threaded into the head and 5/16" fine for the nuts.

 

[slant6billy]

thanks. so of course 5/16 fine thread nuts are exactly what I do not possess in my parts bin. Off to the parts store.