Z28 exhaust manifold crack opinion

[firstgenaddict]

I have heated cast iron exhaust manifolds in the oven on broil that were hot enough that it did not crack when I welded on it so it can be done.
You won't be "chasing" across the part, so you don't have to drill the end. Though if it were mine I may drill and pin that the piece - prior to heating and welding.

[BCreekDave]

Depends a bit on how much you want to hide the fix. If you don't want the outside casting welded you can V the crack on the face that mates with the head and weld that up. Then machine it back flat. Then bore out the bolt hole about 1/4 to 5/16 oversize and lightly press in a very slightly longer steel sleeve. The sleeve will take the stress of the torque on the bolt and the french lock will hide that its been sleeved. The weld will keep the crack from propagating further.
If you aren't worried about looks, it can be V'd out along its length and heated and welded up. You will still need to take a cut across the surface where it bolts to the head.