What's the difference in the crankshaft from a 2pc rear main and a 1pc rear main? can i use the eagle SIR rods on the newer crank or are they a 2pc rear main only type deal. these are the rods that my father is using on his pre-86 355. i, however, have a 91 350. any and all help will be appreciated.

also, what would ya'll suggest for an aftermarket harmonic balancer? any comments on the ati or fluidamper?

 

The rod and main journals are the same on 1 piece and 2 piece cranks. The Fluid dampner is a good one. Not sure on the ATI but if it is SFI rated then it is ok too.

 

thanx

 

Rod journals and main journals are the same. The only difference is how the rear main seal goes in; in the 2-piece design it's (duh) 2 pieces, one goes in the block and one goes in the rear main cap, and the flywheel flange is much larger than the main bearing; on the 1-piece design, there's an aluminum seal housing, and the seal is a steel-clad lip seal like for a wheel bearing or something, and the flange where the flywheel goes is flat and much smaller than the 2-piece design. The 2 types have about the same sealing effectiveness. GM switched purely on the basis of assembly cost.