1966 194. had to have the seals renewed on my head. I got it back from the machine shop, with the two studs removed. Nothing looks damaged. a 3/8-16 hardware bolt goes into both stud locations in the head just fine. the studs which are 3/8-16 by 3/8-24 (I think) will not easley thread into the head, or a 3/8-16 hardware nut. It feels like damaged threads at the tip of the course side of the stud, or a crossthread, but its straight on going in.
has the 3/8-16 side of these studs been factory machined in a way so they don't back out easley. I find it unlikely they are both damaged as either stud is the same in either hole or a hardware nut, and either bolt hole readily accepts a 3/8-16 hardware bolt.
Am I correct or has coincidence beat the odds? Thanks
Maybe someone put metric studs in it?
MBHD
Nothing looks damaged. a 3/8-16 hardware bolt goes into both stud locations in the head just fine. the studs which are 3/8-16 by 3/8-24 (I think) will not easley thread into the head, or a 3/8-16 hardware nut.
So a 3/8 coarse bolt goes in smoothly - but the coarse side of the studs you have will not? Nor will the coarse side of the studs accept a 3/8 coarse nut? I would be scrutinizing the studs not the head.
I would chase the threads in the head with a 3/18 16 tap and shop for some new studs.
Thank you for the replies, I did fail to mention that the studs are original. I did also since the first post, try to thread the nuts on to the clamp side of the studs. Each of the studs 3/8-24 threads are doing the same thing as the course side, and I know it was not doing this, because I was the one to remove the nuts.
Not sure what happened when these studs were removed at the machine shop, the machine shop did not teeth them up wih a set of vise grips. Unless they were mixed up with a Chrysler job in the shop at the same time, these appear correct and have traces of orange, so I assume there mine.
Just wanted to call out to this site before I take a die and destroy an intended inference that has a purpose, perhaps like a rocker arm nut. Probably a little overboard try to save the original studs, its just that they are the original studs. Thanks everyone.
Buy new studs. They are cheap insurance.
I got new studs and I threaded them in after washing the head threads out thoroughly with brake cleaner. Any little particles of dirt in there will cause the studs to not thread in easily. I have that same problem on my new 292. A few do and a few don't and its because there is particles in the threads....and some paint. lol But vice grips take care of the problem.
Just wanted to call out to this site before I take a die and destroy an intended inference that has a purpose, perhaps like a rocker arm nut.
Even with an interference fit - they should still start cleanly. As I understand it interference fasteners are first threaded oversize for entire thread length - and then threaded true for perhaps a quarter of the threads. This allows them to start and then get tighter and tighter as more of the over-size threads are engaged.
I've seen exhaust manifold bolts for big block Chevy that have a large root diameter on the threads, apparently to provide interference fit between minor diameters. Seen it more than once, so I think it was intentional. Anyone else seen this?
Not a six, sorry...