Joe Lucia: Part # Question

[Kurt B.]

Joe,
I have an 8 inch harmonic balancer (Crankshaft Balancer) with a part number stamped on the reverse of 3942538, however I cannot find this part number in my Chevrolet Parts Book for 53-72 Corvette. Does this number mean anything to you and can you identify the correct usage of this part? Could ity be a casting number rather than a part number?
Thank you in advance,
Kurt

[Joe L.]

Re: Joe Lucia: Part # Question

Kurt-----

There was never a harmonic balancer or, for that matter, any other finished part that carried part number 3942538. Therefore, the number has to be a part number for a component of the complete assembly. Generally, the hub section of balancers will have a casting number on the rear which is the part number for the hub only. However, these numbers are usually not stamped but are raised numbers. I've never seen stamped numbers on the rear of a balancer hub.

Sometimes, there will be a DERIVATIVE of the part number stamped on the balancer in some area; usually, it's the last 3 or 4 digits of the part number IF it is stamped.

A few balancers, like many original examples of the GM #3817173 balancer used on your L-79, will have that number embossed on the face of the balancer. However, as I say, I can find no record of any balancer that ever existed of GM #3942538.

[Kurt B.]

Re: Joe Lucia: Part # Question

Joe,
Thanks for the reply. I just looked at it again and it is definitely stamped into the back as opposed to a raised casting number. It is an 8 inch balancer and came off my engine but I replaced it as it did not have the "cooling fins" on the rear. It is stamped on the "rough" surface of the casting on the rear, not on the smooth surface. Guess I have another mystery part.
Kurt

[Joe L.]

Re: Joe Lucia: Part # Question

Kurt-----

It might very well be that what you have there is the replacement 3817173 balancer. These balancers have a different hub section than was used on the original balancer and the number is likley the part number for the hub section only. I've not seen these stamped, but that doesn't mean that none were.

I believe that the reason that the hubs changed over the years (i.e. "finned" and "non-finned") is that, at some point, they "consolidated" the hub section casting for the 63-68 8" balancer with the hub section for the 69+ 8" balancer. The latter balancer didn't have "fins" so when this hub casting started to be used for the SERVICE 3817173 balancers, the "fins" thus "went away". The number you mentioned is a 1969-issued number and it may be the casting number for the 69+ hub.

[Kurt B.]

Thank You, Joe *NM*

[Paul B.]

Re: Thank You, Joe

Kurt, my 42K mile March 19,1968 build coupe, #14222 DOES NOT have a "finned" balancer and I know it is the original one on the car. It is also an L-79 car like yours. There was some debate here a while back on many '68s being noted as NOT having the fins and being "original".

[Kurt B.]

Re: Thank You, Joe

Paul,
Nice to hear from you even if it did just give me a heart attack. I removed the balancer in question from my engine and specifically went out and paid $350.00 for a finned balancer as I thought the one I had might not be correct. Live and learn. Joe can attest to the fact that I spent two years looking for a specific crankshaft not knowing that all the while I had the exact and correct crank in my engine. This restoration project is killing me. (or maybe it is my own ignorance)
Kurt

[Joe L.]

Re: Thank You, Joe

Paul-----

I think that it's very possible, even LIKELY, that 68 L-79's had balancers without the "fins". The 69+ hub (or, another similar non-finned hub) may have been available and supplanted the earlier style by then. In fact, I wouldn't even be surprised if some 1967 L-79s might have originally used the non-finned balancer. Of course, all the 67s would have the "finned" variety now in order to be "correct".

As I've said before, the "fins" seen on the balancer hub are NOT "cooling fins". They have no functionality, whatsoever, as far as coolng is concerned, could have no functionality as far as cooling is concerned, and there was no reason for them to have any functionality as far as cooling is concerned. They are simply reinforcements of some type.

[Gene M.]

Smooth is correct !

Kurt,
Your car is correct with the "smooth balancer". My 68 L79 that I've owned since 71 has the smooth balancer and always did. I was the only person to ever put a wrench to that engine. In fact if one was to check the smooth balancer is just as prevelant as the ribed version in 68 model. And by the way my 68 is an early four thousand build.

[Kurt B.]

Re: Smooth is correct !

Guess I wasted $350.00 for a finned harmonic balancer. Add that to my $1250.00 Rochester carburetor (before rebuilding cost) and you can see why I shouldn't do to many restorations. Good for the economy, but not my wallet. Expensive lessons learned (to late).
Kurt

[Patrick H.]

Re: Smooth is correct !

Kurt,

I probably shouldn't ask about the Rochester question...

Anyway, what you've seen gets back to one thing I've learned over the years: trust your car. Every time you evaluate a part, you have to ask yourself 1) is there ANY chance it's original to the car, and 2) if someone MIGHT have replaced it, then why. I find so many times that the car is "telling" me that it's wearing the right part. I've learned to now "assume" the part on the car is correct unless blatantly obvious otherwise.

You also now understand why you NEVER throw away a Corvette part. You can now re-use your original balancer, if not other parts.

Patrick

[Kurt B.]

Re: Smooth is correct !

Patrick,
You are so correct about saving parts. I purchased this car in 1972 and it had all the correct parts, BUT, I knew nothing of NCRS, matching numbers, etc. and as parts became defective or needed repair, I discarded the old and then went to Chevrolet or the local auto parts store and purchased what I needed. So went the waterpump, master cylinder, carburetor, valve covers, etc and then when I joined NCRS and obtained MANY books, I learned the foolishness of what I had done. Then I spent the last 8 years searching the internet and swap meets to re-buy all the correct parts with date codes and numbers and had everything restored to original such as the $1250.00 carburetor with subsequent $350.00 rebuild cost. In the seventies, we threw these things away and went with Holley dual feed dual pumper to be cool. I now realize cool = stupid on my part.
Who is it that once said "A wise man learns from another's mistake while a fool must learn from his own". I now save everything!!
Fool # 26406