Hi, Putting back together mt 239 flat head and went to torque the last two bolts and they spun!!!
Pulled off manifold and looked at threads and they do not look good.

Should you drill and put in "heli-coil" inserts?? How hard to do??
Can you "devcon" in studs, (should you use studs or bolts??)

The hassle is I just got it back from builder and he missed the bad threads.

 

Go next size up. Drill then tap the drill bigger hole in exhaust manifd.

 

Are these the bolt holes in the block, or where the exhaust downpipe attaches? Are they the front upper exhaust manifold holes in the block? Because those are a different size than all the rest, they are 3/8"-coarse. (it may be both the front port holes on each side, I forget)

 

Yes the front exhaust port but both holes. top and bottom.

Has anyone done helicoil to fix??

 

There's nothing wrong there. Those holes are the next size bigger from all the rest. No worries. Just use the correct bolts and you should be fine, unless there's something else wrong. But try the proper bolts first before doing anything drastic.

 

Front two holes on each side are 7/16 if I remember.......

 

Yep, you're right, I stand corrected!

 

Yep. According to the Ford chassis parts catalog, the smaller ones are 3/8-16 x 1 1/4", the larger ones up front are 7/16-14 x 1 1/4", and all used with lock washers.