ok, i did a search, found a topic same as mine.. but didn't have what i wanted, so, here it goes.

what's the difference in cranks, i know, they each have different sizes of how far the push the rods up & all, but other than that.. is there much of a difference?


also, who makes the best crank? i've heard scat is about same as stock... and eagle makes good stuff. havn't heard about any other companies.. how good they are & all.


also, what's the difference in 1 seal or 2 seal stuf... what is with that?.. i hear people talking about that alot on this site, but still have no clue what it is, or deals with... if it's just seals.. then ok.. but.. where, what, why?

thanks.

 

Cranks come in different strokes, main sizes, rod journal sizes, counterweight sizes, etc.

As far as who makes the best crank, that's hard to say. Callaies makes some very high quality cranks, but they're a bit exspensive, around $1000. Scat makes lower end cranks, they can be had for $200 or so. Eagle is slightly better and a bit more exspensive. For street motors they both make good cranks.

Early blocks came with 2 pc rear main seals, then IIRC in '87 they changed to 1 pc rear seals. The 2 pc seals were internally balanced whereas the 1 pc were externally balanced. You'll have to get the appropriate crank for what block you're using.

 

The biggest difference in aftermarket crankshafts, is the matieral they are made out of. a stock crankshaft, is either Nodular iron, or cast steel. A strong aftermarket crankshaft is forged from 4340 steel.

also, some aftermarket crankshafts are lighterweight, contributing to less rotating mass.

the 1 or 2 piece rear main seal, is what seals the crankshaft where it comes out of the back of the block.

1955-1986 chevy small blocks used a 2 piece rear main seal, 1987-present small blocks use a 1 piece rear main seal.

IIRC the advantage to the one piece is that it seals better.

One piece rear main seal crankshafts have a small bolt circle on the back of the crank for the flyhweel/flexplate. they use a 3" bolt circle.

Two piece rear main seal cranks have a larger bolt circle for the flywheel, it is about 3.75" IIRC.

use a one piece rear main seal crank w/ a one piece seal block

ditto with the two piece.

the "different sizes" you mention, is known as the stroke of the crankshaft.

 

alright, cool.

thanks guys, very much... hit my question dead on the head. :-).