BB exhaust man crack

[Jack O.]

I'm thinking about purchasing a pair of '69 BB exhaust manifolds. The passenger side has a 2" horizontal crack on the outside, under the third runner (counting front to back) about in the middle. The owner says it's a stress crack that is common and that it has never leaked, the crack does not go all the way through. I've only seen pictures. There is no evidence that it has leaked there, carbon, etc. Has anyone had a similar experience with BB exhaust manifolds, i.e. is it a fairly common thing, a stress crack.

Thanks in advance

Jack

[John Wilkes]

Re: BB exhaust man crack

I don't know if it is caused by stress, but the right exhaust manifold on my '72 LS5 has had a crack like that since 1988. Still no leak.

[Al Corelli]

Re: BB exhaust man crack

Yeah, it had no leak when bolted to HIS heads.

Got one like that at a swap meet some years ago. Wrapped it up to transport home, when I got there, it was broken off. Don't bother to weld them, no matter what style of rod you use. This is what I learned;

I bolted the pieces to an old head (milled flat on the ports). I used the proper rod for cast iron. Preheated the whole unit. It broke again, after very little use next to the area welded.

So I defferred to someone with more experience. He said the cast iron had gone through many heating and cooling cycles and had become "crystallized". It would never take a weld.

I am buying the repros. They cost less than the originals on Ebay, and you know their history.

AC