Lighten flywheels

[cHarley32]

I have a 32V. That said, when I acquired it doing a check on the said rebuild. Cylinders bored with not enough clearance. The connecting rods were reversed and to fix bore they will be 70 over. My question is the flywheels have never been lightened. They are C stamped so is it best to go ahead and drill the 4 holes as in Steve’s book and balance some what from or is that close enough.

[Steve Slocombe]

The C means the flywheels are balanced for cast iron pistons. A 1934 Shop Dope says 'it is not strictly necessary' to rebalance the flywheels if changing both pistons, so you could just leave it as is. I've built a couple of engines with the left flywheel machined down to reduce weight, and these needed rebalancing.

[cHarley32]

Thank you for your response Steve.

[T. Cotten]

.. A 1934 Shop Dope says 'it is not strictly necessary' to rebalance the flywheels if changing both pistons, so you could just leave it as is.....

This is confusing, Steve!

Why should you have to change both pistons?

There is only one reciprocating mass in the balancing equation: the total.

Arbitrarily replacing a piston (presumably to an oversize) would lower the factor more than not replacing it.

...Cotten

[Steve Slocombe]

Dear Tom, I guess running one cast iron piston and one aluminum would unbalance the flywheels.

[T. Cotten]

Dear Tom, I guess running one cast iron piston and one aluminum would unbalance the flywheels.

It would certainly change the balance factor, Steve!

Swapping both pistons would change it twice as much.

It would probably still run, because the motor doesn't know it has two pistons.

....Cotten