Harmonic Balancer

[Rob M.]

I read in the TIM and JG that the 300 horse harmonic balancer has a "step" on it. Mine has a step on it and is pressed on. However, I have had a very experienced NCRS member/rebuilder tell me that it is NOT correct. He then showed me several 66's that were at his shop that had harmonic balancers without the step.

Which is correct, step or no step?

May 6th car (no PS or AC).

Thanks in advance, as I don't want to buy a new one if it's not needed.

[Joe L.]

Re: Harmonic Balancer

I read in the TIM and JG that the 300 horse harmonic balancer has a "step" on it. Mine has a step on it and is pressed on. However, I have had a very experienced NCRS member/rebuilder tell me that it is NOT correct. He then showed me several 66's that were at his shop that had harmonic balancers without the step.

Which is correct, step or no step?

May 6th car (no PS or AC).

Thanks in advance, as I don't want to buy a new one if it's not needed.

Rob------


There were at least two harmonic balancers used for 1966 300 HP. The first I know of was GM #3883204. At some point in the model year it was replaced by GM #3896903. The GM #3896903 did not have a "step". I'm not sure about the 3883204 but I think it might have had a slight "step" (more like a combination as-cast and machined outer ring). There might even have been another balancer used very early in 1966 for 300 HP, possibly GM #3861968.

[Rob M.]

Re: Harmonic Balancer

Thanks Joe.

My May 300 horse has the step and my neighbor's June 300 horse also has a step. Anyone out there with a known original in that general time frame? I would appreciate it if you could post what you have for comparison.

Thanks

[Tim E.]

Re: Harmonic Balancer

Rob - Here's a photo of the balancer from my '66 327/300 VIN #24431, engine stamping F0509FE, and birthday 06/17/1966.....no step on mine. The engine is original to the car and I assume the balancer is too. Tim

2003 March 029.jpg

[Rob M.]

Re: Harmonic Balancer

Thanks Tim!

[David L.]

Re: Harmonic Balancer

Enclosed are 4 photos of an original balancer stamped "E 6 F" (May 1966) on the back side that removed from a 1966 Chevrolet 327 engine stamped "T0521HAR" (Tonowanda, May 21, 1966, 327 eng. w/M.T., Rochester carb). I bought the complete engine for $25 back in the 1980's. The 3858180 Tonowanda block casting date is "E 18 6" (or maybe "E 13 6"). Also include was the "4657EF" fuel pump (May 1966), 3875954 intake manifold dated "E 10 6" (May 10, 1966), 1111152 distributor dated "6D20" (April 20, 1966), and 1107320 starter dated "6 E 31" (May 31, 1966).

Dave

[Rob M.]

Re: Harmonic Balancer

Thanks Dave,

Do you know if this balancer was also used on Corvette small block engines?

Thanks

[David L.]

Re: Harmonic Balancer

Rob,

I believe so. My 1966 Chev. Parts Catalog (Oct. 1966) lists GM # 3883204 in Gr. 0.659 as the balancer for 66 ALL, CORVETTE w/forged crankshaft (327) (exc. Sp. H/Per.).

The oil pan is still on my 3858180 "E 18 6" 327 block so I do not know if the crankshaft is forged. I believe that in 1966 the "HAR" stamping is for a 275 HP eng. w/Roch. 4BBL.

Gr. 0.646 in my 1967 Chev. Parts Catalog (Apr. 1967) lists GM #3889304 as the crankshaft for 62-67 PASS., CORVETTE (327)(exc. Sp.H/Per., F.I.) with "Ident. No. 3782680" as the description.

Dave

[David L.]

Re: Harmonic Balancer

Rob,

Here are photos of a balancer for a 66 Corvette block that spent some out in the elements. A fellow NCRS member sent me the photos.

Dave

[Rob M.]

Re: Harmonic Balancer

Thanks Dave, no step and a late car.