2001 Pewter WS6

iTrader: (43)

I am rebuilding my engine. I had my rotating assembly balanced when I built my 408. Here is the question. I am reusing my crank and rods and bought new pistons for my 416. The new pistons are 7 grams lighter then my old ones. Is their a need to get it rebalanced and why??? I am looking at in in the respect that some carbon build up or oil on the piston would make more of a difference than 7 grams. Is it really necessary? I can see if the new pistons were 25 grams heavier or lighter but 7grams seemed pretty insignificant.

LLC

A properly balanced rotating assembly includes oil weight but not carbon build up. It should take a very long time to accumulate enough carbon build up to equal 1 gram in weight. 7 grams is a significant difference. You will never feel the vibrations but your rod and main bearings will.

the_merv

iTrader: (88)

Insignificant sitting still in your hand, move it at 6000+ RPM's, you will notice that difference.

2001 Pewter WS6

iTrader: (43)

You are right, I will have it checked...

caMnaro

iTrader: (24)

see i am in the same boat as you. I took all my parts a machine shop to have checked/balanced with the new pistons. He said they were 8gr heavier then the old pistons and did not need to be rebalanced. I always thought it needed to be balanced every time, so i picked up my parts and now are with someone else getting finished.

Pwebbz28

iTrader: (31)

If 7 grams is insignificant, why weigh the spiro locks for the wrist pins when balancing? Get it rebalanced.