GM sportsman Bow Tie sbc block question
 

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

Re: GM sportsman Bow Tie sbc block question
 

They do come both ways.

Re: GM sportsman Bow Tie sbc block question
 

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 ?

Re: GM sportsman Bow Tie sbc block question
 

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.

Re: GM sportsman Bow Tie sbc block question
 

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

Re: GM sportsman Bow Tie sbc block question
 

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

Re: GM sportsman Bow Tie sbc block question
 

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.

Re: GM sportsman Bow Tie sbc block question
 

can you see the flange on the crank?

Re: GM sportsman Bow Tie sbc block question
 

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

Re: GM sportsman Bow Tie sbc block question
 

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

Re: GM sportsman Bow Tie sbc block question
 

Two piece...

Re: GM sportsman Bow Tie sbc block question
 

L.Fite .. now confused that you think its a 2 piece where as Mike P thinks its a 1 piece .. so a 1 or 2 piece would have different hole dia on the rear flange if one was ordering a new flywheel or flexplate ?

Re: GM sportsman Bow Tie sbc block question
 

Yes, two piece and one piece flexplates are different. Yours must be a two piece (as Eman said) a one piece can NOT have a flange on it.

Re: GM sportsman Bow Tie sbc block question
 

so there must be two hole diameters to locate the center to mount the 6 bolts

Re: GM sportsman Bow Tie sbc block question
 

Yes, that is correct.

Re: GM sportsman Bow Tie sbc block question
 

Sorry...
If the crank has a flange it is two piece like the old BBC/SBC...
One piece has no flange, per se... like LS...

Re: GM sportsman Bow Tie sbc block question
 

Two piece main seal chevy cranks
(play the video to see actual picture)

https://youtu.be/XmYPxvZLu90?t=33

These are picture of two piece crank flanges

Re: GM sportsman Bow Tie sbc block question
 

One piece... No flange...

https://youtu.be/Vai-4Mh5_Io?t=5
Hope this helps.

Re: GM sportsman Bow Tie sbc block question
 

What I have in those crank flange photos is like 327 small j & the 350 photo ..so must be 2 piece ⁹

Re: GM sportsman Bow Tie sbc block question
 

In the original post the question was whether the block was 1 or 2 piece. That is how I answered the question. He did not ask about the crank. If the crank has a flange like the older style then it is a 2 piece seal and will take the older style flex plate.

Re: GM sportsman Bow Tie sbc block question
 

It was my belief that there's only one type of Bow Tie small block and you use the seal adapter to match your crank.

Re: GM sportsman Bow Tie sbc block question
 

thanks guys for all the comments

Re: GM sportsman Bow Tie sbc block question
 

Not to Hi-Jack this thread but do they still make these blocks Thanks

Re: GM sportsman Bow Tie sbc block question
 

I had one that was 2 pc seal only and did not have a seal adapter plate at all. I destroyed that one when a Rod exited the side of the block. I’m