GM sportsman Bow Tie sbc block question

[prostockpete1]

late 90.s GM Bow Tie Sportsman sbc block question .. engine still in car how do I tell if it is a 1 or 2 piece rear seal .. i see the aluminum seal plate behind the crank flange in photos of BowTie blocks in GM catalog but no other data telling me if a 1 or 2 piece without disassembly .. has typical 6 bolt crank flange .. thanks

[Mike Pearson]

They do come both ways.

[prostockpete1]

Yes Mike I know both blocks come both ways .. thats my question how do I identify with out disasembly without pan off .. is the aluminum seal plate blocking a way of knowing 1 or 2 piece without teardown ?

[Mike Pearson]

If it has the aluminum seal plate then it is a one piece seal block. The two piece does not use that aluminum plate. You can run a 2 piece crankshaft in the one piece blocks with the adapter. The work fine.

[prostockpete1]

Mike .. so how come on the GM perf parts site both photos of sportman blocks have aluminum seal plates for 1 & 2 piece

[prostockpete1]

so mike how come on the GM perf parts website they show photos of both BowTie block part # .s of 1 & 2 piece with aluminum seal plates

[Mike Pearson]

If it’s a one piece seal they still have a plate. The two piece adapter bolts to the same flange and has the groove for the two piece seal. That way you can run a 2 piece crankshaft or the one piece crank in those blocks. I have one bow tie block that is for a two piece seal only and it does not have a plate. It has a standard rear main cap. You can only use a two piece seal crank in that block.

[L.Fite]

can you see the flange on the crank?

[prostockpete1]

yes can see flange ..its scalloped around one side of 3 bolts & regular curved edge along where dowel pin would go

[Eman]

If it has a flange a one piece seal can't slide over it.