Balancing Question

[Richard 302]

I've recently swapped out pistons on a previously balanced rotating assembly.  The new pistons, pins, and locks are, on average 13 grams heavier than the original assembly.  The old pistons, rods, bearings, pins, locks, and rings weighed between 1457 and 1459 grams.  The new assemblies weigh between 1470 and 1472 grams.  Is that enough of a difference that I need to have the rotating assembly rebalanced.

[bcmiller]

I would ask your machinist.

Personally I wouldn't worry about it if it was mine - unless it would see frequent blasts above 7000 RPMs.

[MO]

If you are going to balance an engine assembly, why wouldn't you balance all reciprocating parts? As stated, it might be ok, but I personally would not chance it. But I'm kind of a nut when it comes to details.