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Picked up a NOS Harmonic Balancer, #3817173. Box shows GM production in Canada with an order date of 3/13/2003. My question/concern is that I cannot find the above part# anywhere on the balancer? The only numbers I have found are on the inside, one is 2538 and the other is 5K08 or 5KOB. Does the below picture look to be the correct balancer?
I don't think your balancer is what the box says – the 3817173, I believe, is a "finned" balancer. Shown as the top one in the pic below. From what I've read, the over-the-counter replacement did not have the fins - like the lower balancer.
That damper looks similar to the one on my 1968 L79 327 engine. It was originally out of a 68 Chevelle and the L79 was listed as 325 horsepower with 11 to 1s.
I don't have a pic of the backside of the damper but there are no fins.
Boy this takes me back many years or should I say many many many years. Fined vs non fined balancers: Back when I had the time and health to work on these small journal 327 we learned to watch the timing mark on the 8" balancers. The keyway in the fined balancers was approximately 8 degrees off of alignment with the timing mark. However the keyway and alignment mark were aligned in the non fined balancers, This seemingly slight differences made it impossible to time your engine with the wrong balancer. I once bought a rebuilt engine that only needed the correct balancer to get it to run correctly (or by the numbers).
Boy this takes me back many years or should I say many many many years. Fined vs non fined balancers: Back when I had the time and health to work on these small journal 327 we learned to watch the timing mark on the 8" balancers. The keyway in the fined balancers was approximately 8 degrees off of alignment with the timing mark. However the keyway and alignment mark were aligned in the non fined balancers, This seemingly slight differences made it impossible to time your engine with the wrong balancer. I once bought a rebuilt engine that only needed the correct balancer to get it to run correctly (or by the numbers).
My '77 Corvette P & A catalog lists 3817173 as the balancer for 62-68 w/ FI, Sp. H/Per, (327), and there's also a note to use 3883206 key with this balancer. So it looks like what you have is the real deal. The reason you don't see a part number is because what you have is an "assembly" made up of three separate parts... hub, rubber ring, and iron ring. The 2538 could be the last four digits of that individual part.
I'm not sure about the cast in characters... 5K03 could be 5 November 2003 (I is typically skipped so as not to confuse with 1, so K would be November), but that's prior to the pull date, so no dice.
What surprises me is that GMPD would still have this part in the early 2000s whose last use was over 30 years prior.
[aQUOTE=SWCDuke;1608286063]Those degree markings are not OE. I assume that the unpainted painted part is different than the painted part. Maybe you could explain in more detail.
Duke[/QUOTE]
Same part, I stripped the damn thing to find any numbers to help me identify what I have!
So someone who possessed that part in the last 21 years had the degree marks added, except the notch that goes clear across. That's the factory index mark that indicates TDC when aligned with zero on the OE timing tab that's tack welded to the timing chain cover. Said person also probably painted it. I don't think the service part would have been painted, but if so it would not be nearly as nice.
Thanks for the insight! So please educate a newbie here….is it usable for a 365 engine build? If not, what engine could use this?
It appears you, CTVandy23, have the later harmonic balancers with the 0 degree timing mark offset 9 degrees from the keyway which is TDC +/- 2 degrees. These #3817173 balancers were used with the HP engines which utilized the long water pumps. I believe they were still cast as #3817173, but may be wrong. They did not have the cooling fins and have holes around the perimeter of the hub. This balancer must be used with the correct timing chain cover or aftermarket timing tab to get correct timing.
From the Google search I have done, the 62 to 65-66 # 3717173 balancers had the cooling fins and the timing 0 degree mark was about 2 degrees offset from the keyway. The GM parts catalogs show the #3717173 balancers were used from 62 to 68. They were used on the HP 350 HP and 365 HP 327 engines and the 302 engine. Most engine builders recommend this balancer for all HP engines over 300 HP. I ran this on a 302 engine and have the later model on a 350. I don't know of any reason not to run it on any SB.
It seems sometime in 66 or 67, they eliminated the fins and it may also be when they drilled the holes around the perimeter of the hub ring but I could find no definite information on this change.
Here is the #3817173 balancer I have: Finned 62-66 Almost non-legible due to casting variations. 3717173 137500 2 I don't know what the square in the number means and the marks / numbers in it. Also, the CS stamp is a mystery.
Ctvandy23, Your balancer may indeed be an aftermarket or maybe later balancer from GM as indicated on the box. They were very popular and used on all HP engines and used thru the 70s. I am surprised GM seems to have kept using the #3817173 number with the elimination of the fins and change in timing mark location.
The Damper Dudes web site shows a new 8" balancer available that they seem to manufacture or at least retail. JEGS and other retailers also sell a new 8" balancer identical to yours and may even have the degree stampings. https://damperdudes.net/harmonic-balancers/chevy/
Harmonic Balancer
