Yes, But Be Sure To Relocate The Timing Mark
T_: The crank I'm using came out of a '68 4-bolt main truck block and I'm not sure what size balancer it had on it. I have an 8" balancer, can I use it on my engine or will it mess up the balance of the engine? Can you can interchange the 6" and 8" balancers no matter what the crank originally came with?TS: Yes, you can interchange the six and eight inch balancers as long as the eight did not come off a small block 400ci crank. The 400's are balanced differently from other small blocks. Balancers from 400's usually have holes partially drilled in the front. The eight inch will not throw your balance off; they are usually used for high performance small blocks running high rpm's. Make sure the timing mark on the chain cover lines up to the new balancer.
DS: If you are using the harmonic balancer, either a 6 3/4 or 8", the corresponding timing mark should be used. There is one warning: the timing mark positioned after 1969 is relocated a little, and if using a balancer from a 1969-present small block, be sure to get the timing pointer also, or buy an aftermarket one from Mr. Gasket. The 400ci balancer has a counterweighted indentation on the outside of the balancer, and when compared to a 350, the balancer measures 8 inches. The 350 balancer is smooth all over, but the 400 has some weight removed from the inertia ring. There is one Hot Rod article about the 383ci vs. 454ci engines, and on the March 1992 cover, look at the small block carefully. You will notice the indentation that I mentioned. The timing pointer for a 1968 small block might be available from GM, but I think that this part might be discontinued. My recommendation is to find another 1968 small block with a bolt-on pointer for use with the 8" balancer, and pirate it for use with your motor.
Archivist: Tom Wilson
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