Matching metals

[dhopkins]

I am rebuild my 69S engine. I am thinking of replacing the chain housing. Since the case is mag, I assume the chain housing is mag. My mechanic says mag chain boxes are not worth a darn and I should replace it with a aluminmum case. But I think the matching metal that expand at different rates is a problem. The reason I would replace the housing is the it interface b/t the housing and the case may be a source of an oil leak I need to get rid of. Ideas?
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[nick-moss]

I think that the ally and mag housings have differend mountings so are not interchangable.

[dhopkins]

My mechanic says that the original chainboxes on mag engines often warp and
he replaces them with a chainbox from an SC. He says he has did it many times and it works.

[Steve@Rennsport]

My mechanic says that the original chainboxes on mag engines often warp and
he replaces them with a chainbox from an SC. He says he has did it many times and it works.

Don:

Your mechanic is a wise & enlightened person; he is right.

Aside from the color differences between the magnesium and aluminum chainboxes, this is really a good upgrade and cures/prevents a whole myriad of oil leaks.

SC chainboxes fit all of the magnesium cases (1R, 2R/3R, 4R/5R, & 7R) and can be retrofitted to the early sand-cast cases for a more leak-free engine.

(edited for kenikh )

[kenikh]

Don:
SC chainboxes fit all of the magnesium cases (2R/3R, 4R/5R, & 7R) and can be retrofitted to the early sand-cast cases for a more leak-free engine.

You said all, but didn't mention 1R mag cases specifically. I assume it works on these as well?

[nick-moss]

Whoops. When I said they were not interchangable I was refering to pre 68 ally chain cases.