after fully assembling my block...the pistons were not sitting right and it was brought to my attention i may have a b16 crank instead of the ls crank i need. the only difference i can see is in the second picture there is a difference between the fins on the crank. the crank on the left is the one that just came outta my block....

 

If you still have it in the block measure from the deck to top of the piston at top dead center and at bottom dead center.Subtract the smaller from the bigger and that's the stroke of the crank.3.047 for b16,3.433 for b18c,3.504 for b18a,b.Left one looks like b16,right is 18a,b

 

well the crank i pulled out left the pistons sitting like this at tdc....


which is very wrong.

 

Yup that looks like a b16 crank in a b18 block.Your sure you have b18 rods and not b16 (pr-3).

 

yeah the rods are stamped pr4 so they are definetly ls rods.

i got shafted on ebay and thought i was uying an ls crank....guess not.