C1 harmonic balancer difference explanation

[King M.]

I have a question in regards to c1 harmonic balancer (3760584 and 3764318). Outside of their physical appearances being the step in front or the step in back, is there any difference mechanically? Ie, weight, timing markings etc between the high and low horse balances? I would appreciate any knowledge on these. Will the low hp balancer perform the same on a 270hp engine as the 318 balancer?
Thanks
King

[Joe L.]

Re: C1 harmonic balancer difference explanation

I have a question in regards to c1 harmonic balancer (3760584 and 3764318). Outside of their physical appearances being the step in front or the step in back, is there any difference mechanically? Ie, weight, timing markings etc between the high and low horse balances? I would appreciate any knowledge on these. Will the low hp balancer perform the same on a 270hp engine as the 318 balancer?
Thanks
King

King------


Well, I can tell you this much: often times the difference between balancer part numbers is related to "tuning". Just how this "tuning" difference is actually accomplished, I do not know. Sometimes, balancers will be physically identical but have different "tuning" and part numbers. The SHP and HD big block balancers are an example of this. Side-by-side, one could discern no difference.

Whether the two balancers you mentioned could be interchanged I cannot tell you for certain. However, I can tell you this: GM #3760584 was discontinued in February, 1962 and replaced by GM #3817684. GM #3764318 was discontinued in November, 1962 and replaced by GM #3817684. So, both balancers were replaced by the same balancer.

GM #3817684 was discontinued in November, 1964 and replaced by GM #3861968. The latter was discontinued in November, 1965 and replaced by GM #3861970. The latter was discontinued in June, 1971 and replaced by GM #3896904 which was discontinued several years ago without supersession.

The above implies, but does not confirm, that the 3760584 and 3764318 could probably be used interchangeably. There might be some downside to this but I doubt it would be significant.

I can you for certain that ALL of the above referenced balancers would have the timing mark in the same location, aligned with the crank keyway.

Dorman and others offer harmonic balancers equivalent to the 3896904 and they are fairly inexpensive. If I were going to replace a balancer on a 283 cid Corvette and I was not concerned about original configuration, I would either look for an NOS 3896904 or use one of the aftermarket balancers.

Here's an example of an NOS GM #3896904 so you can see the configuration. The 3817684, 3861968, and 3861970 are similarly configured.

https://www.ebay.com/itm/1957-1967-NOS-Corvette-Chevy-Chevelle-Crankshaft-Balancer-Damper-3896904/163576314018?hash=item2615e878a2:g:XZ4AAOSwhRdba6kI:sc:USPSPriority!94539!US!-1:rk:3:pf:1&frcectupt=true