Manifold Repair

DentalDart said
Thanks! Im going to try and get those muggy sticks and take them to my uncle's shop one day.

Maybe they'd be able to mill it, sand blast it and powder coat it all there too. I know his company does all those things, so we will see what he says.

Honestly. Moparmike has explained what needs to be done - so find a shop with an oven or equivalent for this type of cast iron repair.

MoparMike1974 said
V out the crack, drill crack stops at each end, pre-heat part then weld with nickel rod. Cover part with sand so it can cool slowly. This is the old tried and true method for cast.
However, like mentioned here mig can repair cast well. It really depends on if its a high stress part. The problem with a manifold is they are thin and they expand and contract all the time.

If its for your own use and are OK with using gaskets well OK. But IMO, its worth checking the face on a spare head or super flat surface. Then if needed find someone to mill or lap it.

For coating, especially since not every little rust pit has been cleaned, might try a non-paint cast iron 'sealant' like Eastwood and Bill Hirsch sell. Supposed to make touch up easier.
When I've painted 340 exhaust manifolds after sandblasting, I used Bill Hirsch's exhaust manifold paint. It last decently but eventually spekles of rust come through -especially near the heads. This was on a car that was sometimes used every day, along with some track time etc.