The Stovebolt Site Forums The Shop Area Engine Shop Exhaust Manifold Repair Options

It seems that one of the ram horn exhaust manifolds I pulled off the wall to use has two of the three stud holes slightly wallowed out enough to prevent the new studs from securly threading into the exit flange.
Other than buying a replacement manifold or welding the studs into place, yuck, what other methods of repairing these two holes do I have available? These are cast iron manifolds with the rear swept exits.

You could try helicoils. I have used them in heads so they can get hot. An older trick is to cram foil in there and then the threads will catch on the foil and go. You could also get some metric studs that are slightly larger and use them after re-tapping. I have done that as well. JB Weld might work - people have used it on blocks. One other option is to change to a regular bolt - pass it through and then put a nut on the end of it. I have done that as well.

You might try getting some studs that are bigger on th short thread end tap to the next size the have the original stud size still where thy go thru your xhaust pipe flange....Ronnie

Hy Houston 54, I repair these holes by brazing around the outer circumference of the hole then drill and retap.

JB weld will not work on high heat, it just melts away.

Super250six

If the hole isn't washed out too big a helicoil will give a permanent and virtually invisible repair. For example if the stud is 3/8" fine thread the drill size would be 25/64" or .390" If the hole is larger than the drill size another method should be used. Here's a tap drill chart for helicoils.
http://www.carbidedepot.com/formulas-tap-helicoil.htm

Curt B.

I'd say the helicoil is your best bet. Helicoil is a brand name so you can find the same product sometimes under the name "recoil" & save a few bucks.

Half of the problem has been solved as I drilled and tapped one hole for 7/16-14 thread and got a replacement stud from a local muffler shop. The other hole is going to be more of a problem.