I'm in the process of rebuilding my 383 and have a question about the balancing of the engine. I am planning to reuse the crank and h beam rods as well as get the same Je SRP dished pistons that I currently have in the car. Assuming the car was balanced properly when initially built back in '01, (don't see any signs of improper balance on the parts) any concern with just putting in new pistons/rings/bearings and not balancing it again?

 

I would balance again if getting new pistons. Take a look at the old pistons - they were probably ground on the bottom side as part of the balance job.

 

Check the weight of the old pistons and if they are close no need to rebalance.
SRP's always come in close to the weight from batch to batch.

 

I agree...pistons are probably really-really close in weight....I'm saying the balancer will sometimes remove weight from pistons to balance the whole package. I just had my 355 balanced when I re-built it and they drilled holes in the crank counterweights - but also did some grinding on some of the pistons on the underneath side of them. If I were to replace pistons with new ones - my balance job would be in the toilet.

 

I was thinking of getting a gram scale and trying to match up each piston as closely as possible if they did vary a little.

 

Well I weighed the old pistons with the pin and clips in (no rings) and they were 600 grams. The new pistons (same JE SRP model number, but originals were 6 years older) with pin and clips weight in at 612 grams. I weighed the old vs new pin alone and both were 130 grams so the extra weight is from the piston.

So........is this enough difference that it would cause a problem? If necessary I will shave a little weight out with a dremel because the machine shop is backed up and I have spent enough on this car for this year that a full internal rebalance isn't desirable.