Rear Main

[turbodave]

This is the rear main out of my sleeved block.

[KendallF]

This is the rear main out of my sleeved block.

I don't know why in heck they put a cast cap on there. It appears to have been welded on the lower portion to fit, as well. Take a picture of the inner cap showing the lip for the seal; does it even match the block? The block appears to have the lip for the BBC style seal, and the cast cap will take the stock seal. The BBC seal has a groove that goes over the lip in the cap; the stock style just fits in the groove.

I think I'd look for a steel rear cap from a blown up block to have fitted to that block.

I've attached pics of my steel rear main on my on-center and a cast rear main on an early off-center to show the differences.

[turbodave]

Thanks Kendall, I was hoping to illicit comments on the rear main.

Both blocks have the cast rear main cap. But they are in fact cut to match the block in the seal area. That is, they are made for the chevy big block seal. So yes, the caps match the blocks in that respect. Sorry the picture didn't show that part very well.

The rear cap for the all aluminum block fits like a glove! but it's also cast, and that block hasen't been align honed yet, nor does it have any studs yet.

This block pictured has had an align hone done to it.

My concern is, I'm wondering if this cap will seal with the side seals in place. I can't remember how much of a gap the side seals are capable of sealing (and holding), even with the "nails" driven down into them.

Guess it's not a bad idea to try and find a billet rear main or two. Think I'll put some inquiry's in the parts wanted forums and see what happens. Don't know what one would be worth though.

My thoughts are to try and build one of them (if I ever get going) up to around 650HP (race trim). Should the caps that are there support that?

Most importantly, if I HAD to use the cap you're seeing, and assuming it seals (???), would it be stable enough for that?

Here's a better picture of that cap.

[KendallF]

Thanks Kendall, I was hoping to illicit comments on the rear main.
SNIP>>
My concern is, I'm wondering if this cap will seal with the side seals in place. I can't remember how much of a gap the side seals are capable of sealing (and holding), even with the "nails" driven down into them.
SNIP>>
My thoughts are to try and build one of them (if I ever get going) up to around 650HP (race trim). Should the caps that are there support that?

Most importantly, if I HAD to use the cap you're seeing, and assuming it seals (???), would it be stable enough for that?

Here's a better picture of that cap.

You won't elicit anything illicit from me.. :joint: I would test fit a side seal in there and see how much of the gap it fills. If you use it, I think I would get out the silicone caulking gun, just to be safe. If it fits decently and it's round, and, yes, if it seals, I can't imagine it'd be a problem.

[turbodave]

Thanks Kendall ;)

Guess I'll have to see if the local parts house :rolleyes: has any Buick rear seals around. As I understand it, I'll need a Buick rear seal to get the side seals, and most any BBC to get the rear crank seal. ?

[turbodave]

You won't elicit anything illicit from me.. :joint: I would test fit a side seal in there and see how much of the gap it fills. If you use it, I think I would get out the silicone caulking gun, just to be safe. If it fits decently and it's round, and, yes, if it seals, I can't imagine it'd be a problem.I might just try that. Somebody went to a lot of trouble to get the base to fit the block!! It's an incredibly tight fit, so there should be no side/side movement.
As you know, my goals (if I ever realize them) are to build one of these to make ~700 HP. So I suppose that one cast cap should be OK if I can't find a decent billet piece.