Help ID'ing harmonic balancers

[Dennis O.]

Since I turned 70, I've come to realize that I won't be here forever, and have started to think about what's going to happen to all my "stuff" after I'm gone. One of my worries is that some potentially valuable rare parts will be discarded, simply because no one will know what they are. With this in mind, I have purchased a bunch of sturdy manilla tags with wire attachments and am going through my "stash" labeling everything that is not easily identifible.

Yesterday, I ran across these two harmonic balancers. I cannot find any part numbers on them. Since the only SBC's I have owned were either in Corvettes or boats, it would seem that these may be corvette parts. (I have owned my '67 L79 and '68 300 HP car for over 25 years.) Surprisingly, I have no recollection where these came from. I have had "slipped" harmonic balancers on both cars over the years, but I'm sure I sent the originals out to be rebuilt.

Can anyone identify these? The nicely painted one is 8" and tyhe other is 7". In the alternative, can anyone tell me where the part number should be, so I can maybe strip some paint and look. Thanks in advance.

[David L.]

Re: Help ID'ing harmonic balancers

Dennis,

There should be a partial part number and date code stamped on the balancer. You might have to remove some paint.
I have studied balancers in search of the correct balancer (GM # 3947704) for my 1970 Camaro SS350 long term project as well as balancers for mid-year Corvettes.
I have two original 3947704 balancers (8" dia.). I found one at a swap meet that is stamped "7704" and "B9F (Feb. 1969). The other balancer that is stamped "7704" and "AS0" was removed from a 1970 Monte Carlo w/300 HP eng. Both have a "3896966" casting number.

I also have a 3947701 balancer (6 3/4" dia.) from a 1971 Chev. 350 eng. that is stamped "7701" and "1S0" and a 1969 Chev. (307) balancer that is stamped "7706" and "J8F" ("J8" = Oct. 1968, "F" = manufacturer???).

I believe that there were two manufacturers: "F" and "S".

Dave

[Dennis O.]

Re: Help ID'ing harmonic balancers

Dave,

Thanks for the input. Where should I look for the numbers? Inside, outside, on the lip?

[David L.]

Re: Help ID'ing harmonic balancers

Generally on the front side. Use a small wire brush as sometimes the stampings are hardly noticeable. The "7704" and "2222" balancers are about 1 3/8" thick. I believe that the 3817173 (67-68 Z28) , "7708", and "2224" balancers are 1 11/16" thick.

[David L.]

Re: Help ID'ing harmonic balancers

The 6 1/8" balancer that I removed from a 1966 Chev. 327 engine did not have a part number stamping, just a date code stamping, "E6F" (May 1966, "F" was for the manufacturer). The block, the 461 heads, carb, fuel pump, starter, flywheel, and alternator were all dated in May 1966 when the engine was assembled. I paid $25 for the complete engine back in the early 1980's.

Dave

[Cecil L.]

Re: Help ID'ing harmonic balancers

The first balancer in your pics looks like the 7" SHP balancer for solid lifter 409's.