piston weight /engine balance

torsional harmonics?

To get a well balanced engine you must weigh the Pistons and get them as close as possible to equal weight. The rods need to be weighted on each end and kept as close as possible to each other, finally the crank needs to be spunup on a balancer. If the pistons are too heavy extra weight will need to be added to the crank weights. Small amounts of weight can be removed from the piston skirt and gugeon area in very small amounts to get them closer to original specification.

If the engine is out of balance you will notice a harmonic, depending how much out it is will mean a bigger or smaller vibration. As you rev the engine the vibration will go away and come back again as the revs get higher.

My advice would be to take the pistons to a good engine shop and get their advice on if that smaller amount will make any difference as there is a tolerance that you can get away with.

Noel

Dustproof wrote:

If the pistons are too heavy extra weight will need to be added to the crank weights.
Noel

Not on inline and flat fours.

APE Jay wrote:

Dustproof wrote:

If the pistons are too heavy extra weight will need to be added to the crank weights.
Noel

Not on inline and flat fours.

2 going up, 2 going down, they cancel each other out