Porsche 914/3.1

[ForcedFirebird]

If they are heavier or lighter than the original pistons. The 1988 fiero engines are internally balanced.

Correct me if I'm wrong, but pistons are not rotating mass, they are reciprocating mass. As you move down the rod, the weight will become rotating mass until you get to the big end of the rod where it becomes rotating mass.

The 3.1 RWD cranks are balanced, or appear to be with the holes drilled in them. If memory serves me correctly, it's only the small journal cranks that were not neutrally balanced, and even required a different flexplate to compensate fot it.

[Stevesr]

Porsche 914/3.1

[QUOTE=ForcedFirebird;373941]Correct me if I'm wrong, but pistons are not rotating mass, they are reciprocating mass. As you move down the rod, the weight will become rotating mass until you get to the big end of the rod where it becomes rotating mass.

I agree,if any "expert" knows for sure,chime in. My crank "appears" to be balanced,it has holes drilled in the counter weights. This motor came out of a 91 Corsica with auto trans. The flex plate had no weights attatched.Not sure about the torque converter.Logic would dictate that if the rods and pistons with pins all weighed the same the crank would only need balancing?

SteveSr

[Superdave]

If it's out of a 91 Corsica it's internally balanced.