L-68 harmonic balancer

[Tim Sargent]

What is the stock correct diameter and thickness of the harmonic balancer for a 1967 L-68 engine? Also is the crankshaft cast or forged steel?
Thanks
Tim

[Joe L.]

Re: L-68 harmonic balancer

Tim-----

Your engine originally used a 7-1/16" OD harmonic balancer which was 1-3/8" in thickness. This balancer was GM #3860008. In fact, it's still available from GM for a current GM list price of $281.22.

Your engine originally used a forged steel crankshaft. Most 427 crankshafts were forged steel.

The only question is whether your engine has 4 bolt main cap configuration, or not. Some L-68's had 4 bolt; some did not.

[Tim Sargent]

Re: L-68 harmonic balancer

Joe, thank you for your response, the block has two bolt mains. It curretnly has a large 8" 1 3/4thick balancer. If I change to the correct balancer you reference, will I have to rebalance the enginesince it is internally balanced?
Tim

[John H.]

Re: L-68 harmonic balancer

The "balancer" on a 427 (or on any pre-'85 small-block except the 400) has nothing to do with engine balance - it's a torsional damper; replacing your current 8" damper with the correct 7" damper will have no effect whatsoever on engine balance.