well i got a set of forged pistons for the 82's engine and got my regular machine shop to size up the block for the new pistons etc. however just as he is finishing the block for me, he informs me that with such a light piston I will need to rebalance my rotating assembly. I guess they are 40 gramms lighter than my old .020 pistons despite these new ones being .030.

I've never heard of an engine needing balanced over a mere piston swap especially since they are lighter?

is this a nessesary step? my city does not have any shops with the equipment to balance an engine. Is it worth it to go out of town and get it done?

 

40 grams is almost 1½ ounces each. That's kind of alot to change something spinning around at 6000 RPM, don't you think?

I'd get it done if it was mine.

 

And, you don't actually think the stock crank and pistons were really balanced, do you? I've seen stock assemblies with up to 26g variation within the same "set". It's always a good idea to spend a little extra time balancing the parts, then counterbalancing them with the crank.

 

makes sense

I've been involved with half a dozen engine builds and this is the first time (except for the 383 build up) that I've heard that balancing the crank was nessesary.

definatly can't hurt to have everything balanced though. I agree with that.

 

Balancing is gooood Between the 305 I used to have and my current 350, the 350 runs much smoother as in it has no weird vibrations.