Need high hp harmonic balancer

[Gary H.]

Re: Need high hp harmonic balancer

[Gary H.]

Re: Need high hp harmonic balancer

[Cecil L.]

Re: Need high hp harmonic balancer

Mine with the holes in the outer ring came off a 60 335hp 348. Perhaps the difference between the 283 balancer and the 348 balancer is the outer ring. It would seem that higher rpm would require more mass so the 270 hp 283 would be solid whereas the lower revving 348 might have the lightening holes. The hub appears to be the same. The overall diameter appears to be the same at just under 6 1/8th .

[Gary H.]

Re: Need high hp harmonic balancer

Outside diameter measures 6 1/16 . So, with that 375??066 casting number can anybody say with reasonable confidence that this is an original 3764318 balancer??? The one on page 74 of the JM shows 3 round holes vice the 3 large D shaped holes (spoked design). Thanks again, Gary

[Loren L.]

Re: Need high hp harmonic balancer

Hi Guys. I have one identical to Cecil's except no holes on the outer perimeter. Casting number appears same as Cecil's also (bolt hole drilled in middle of cast number obscures couple digits). Anybody know correct application? Thanks, Gary

3764318 first appears in the Apr 59 Pts BK, but is called out as applying to 59 Pass/Corv with high lift cam and the 59 psgr 3 X 2 setup. AT THIS TIME 57-9 PASS/CORV WITH FI & HL CAM ARE STILL BEING SHOWN AS BALANCER 3742986
By April 60, 3764318 is listed for 57 Pass w/TG(turboglide),57-60 pass/Corv w HL cam,& 59/60 pass with 3 X 2

By Oct 61, 3764318is being shown for 1>57/8 Pass/Corv w H/L cam; 2>59/61 pass/Corv with H/L, high perf & Spec HP;3>59/61 pass w 3 X 2;
4>61 pass 409 (lst design) AND 62 Corv with HP, SHP & FI

I suspect that the listing in the 59 pts book leaving 57-9 w FI & H/L
w Balancer 3742986 IS IN ERROR with regard to the 59 Pass/Corv FI-H/L
cam - it shld be under 3764318. I also doubt that the 62 Corv should be included.

My guess is 59/60 Pass/Corv with H/L; 61 Corv with H/L cam; 59-61 348 w/3 X 2 & 61 pass with first design 409.

[James A.]

Re: Need high hp harmonic balancer

Attached is a photo of three balancers I looked at in Carlisle. The upper two were claimed to be original 290HP balancers and the bottom one was a reproduction. I don't know if the claims were true or not. Just thought I'd add this photo to the discussion.

[Joe L.]

Re: Need high hp harmonic balancer

All------


There are a total of SEVEN different part numbers in the "lineage" of the balancer in question. They are as follows:

3743319

3742986

3764318

3817684

3861968

3861970

3896904

I believe that at least the first three are all of the general configuration pictured previously by others. However, there may be differences (such as the outer ring holes) between them.

The next 3 were used in PRODUCTION, successively, for 1962-65 Corvettes with 250 and 300 hp as well as other applications and became, successively, the SERVICE balancers for 59-61 Corvettes. I am not sure just how these balancers were configured.

The last part number, GM #3896904, was never used in PRODUCTION for any Corvette but is SERVICE for all 57-61 Corvette applications. It is a 6-1/8" OD balancer with a "full wide" 3/4" outer ring.

[Cecil L.]

Re: Need high hp harmonic balancer

Attached is a photo of three balancers I looked at in Carlisle. The upper two were claimed to be original 290HP balancers and the bottom one was a reproduction. I don't know if the claims were true or not. Just thought I'd add this photo to the discussion.

The balancer in the upper left is the same as used on the 63 340hp 409.

[Loren L.]

Re: Need high hp harmonic balancer

Attached is a photo of three balancers I looked at in Carlisle. The upper two were claimed to be original 290HP balancers and the bottom one was a reproduction. I don't know if the claims were true or not. Just thought I'd add this photo to the discussion.

If you measure the top two and come up with a 4 5/8" diameter, you are looking that the LOW HP balancer. All three of these are wrong for HP.

[Joe L.]

Re: Need high hp harmonic balancer

The balancer in the upper left is the same as used on the 63 340hp 409.

Cecil-----


Two different balancers were used for the 1963 340 hp 409. If the 63 340 hp 409 originally used the balancer configured exactly like the one in the upper left of the photo, then that balancer is either the GM #3830820 or 3838371. If so, the center HUB will be of 5-1/2" OD. Neither balancer was ever used on a Corvette.

The 59-61 Corvette SHP balancers, which were shared with 59-61 high performance 348's, had a HUB that was 4-1/2" OD.

[Loren L.]

Re: Need high hp harmonic balancer

I guess I need a new definition of "hub".

Cecil-----


Two different balancers were used for the 1963 340 hp 409. If the 63 340 hp 409 originally used the balancer configured exactly like the one in the upper left of the photo, then that balancer is either the GM #3830820 or 3838371. If so, the center HUB will be of 5-1/2" OD. Neither balancer was ever used on a Corvette.

The 59-61 Corvette SHP balancers, which were shared with 59-61 high performance 348's, had a HUB that was 4-1/2" OD.

[Joe L.]

Re: Need high hp harmonic balancer

I guess I need a new definition of
"hub".

Loren-----


Most (but not all) balancers consist of 3 parts: the hub, the elastomer (i.e. rubber), and the ring. The hub is the section that's "inboard" of the elastomer. The ring is the section "outboard" of the elastomer.

[Cecil L.]

Re: Need high hp harmonic balancer

Cecil-----


Two different balancers were used for the 1963 340 hp 409. If the 63 340 hp 409 originally used the balancer configured exactly like the one in the upper left of the photo, then that balancer is either the GM #3830820 or 3838371. If so, the center HUB will be of 5-1/2" OD. Neither balancer was ever used on a Corvette.

The 59-61 Corvette SHP balancers, which were shared with 59-61 high performance 348's, had a HUB that was 4-1/2" OD.

Joe,
I don't have the part number for this but it is an original balancer from a 64 340hp 409 and I believe the 63 to be the same. As you can see the hub is not 5-1/2. The visual cues as I have understood them, are the "U" shaped cut-outs in the surface between the large lightening holes and the outer edge of the hub. Also the small stepcut on the rear of the outer diameter of the ring. In short, I suspect the lo perf 409 continued the common useage of balancers with the smallblock as was the case with the lo hp 348.
I haven't found the 3830820 part number in my P&A references but I don't have good ones for the 63-64 time frame. It seems there just isn't much detail on things like balancers and bell housings in most of the reference material.. Even Nolands great works didn't seem to have much.
I suspect that there were several variations within the same part number for minor changes in castings and rings (with holes, without holes) or even possibly a change in suppliers. There are plenty of examples out there of different parts with the same part number. The part number may have remained the same but the part could have changes throughout the 4 or 5 year production span of the part. Just my guess.

[Joe L.]

Re: Need high hp harmonic balancer

Joe,
I don't have the part number for this but it is an original balancer from a 64 340hp 409 and I believe the 63 to be the same. As you can see the hub is not 5-1/2. The visual cues as I have understood them, are the "U" shaped cut-outs in the surface between the large lightening holes and the outer edge of the hub. Also the small stepcut on the rear of the outer diameter of the ring. In short, I suspect the lo perf 409 continued the common useage of balancers with the smallblock as was the case with the lo hp 348.
I haven't found the 3830820 part number in my P&A references but I don't have good ones for the 63-64 time frame. It seems there just isn't much detail on things like balancers and bell housings in most of the reference material.. Even Nolands great works didn't seem to have much.
I suspect that there were several variations within the same part number for minor changes in castings and rings (with holes, without holes) or even possibly a change in suppliers. There are plenty of examples out there of different parts with the same part number. The part number may have remained the same but the part could have changes throughout the 4 or 5 year production span of the part. Just my guess.

Cecil-----


Late 1963 through 1965 340 hp 409 used the same balancer. GM says that the balancer had a hub that was 5-1/2" OD. I don't know anything about the balancer other than what I'm told. It may be that the 5-1/2" hub OD spec is incorrect. They do make such errors now-and-then. The 3830820 was the balancer used for early 1963 340hp 409.

In any event, this balancer was never used on any Corvette.

Yes, it is very possible for a part to change over a period of time even if the part number does not change.

[Tom O.]

Re: Need high hp harmonic balancer

Joe, Loren, and Everyone,

Thank you for the excellent information.

Tom