Harmonic Balancer Question
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Joined: Oct 2002
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From: Denver CO
Harmonic Balancer Question
Howdy All,
I replaced my BB camshaft this past weekend. Went from a 262 duration to a 223 duration for improved idle. Also, solved my dieseling problem as I lowered the idle speed.
Anyway, during the teardown we discovered that the harmonic balancer is only a 7 inch balancer. The pro that was helping me said I should have an 8 inch.
I'm dealing with a 1974 block/crank 454 that was transplanted into my '66 coupe.
So, do I need to replace it with the proper 8" balancer or let it go? I'm not racing, if that's an issue.
Thanks in advance for the advice.
Plowboy :cheers:
I replaced my BB camshaft this past weekend. Went from a 262 duration to a 223 duration for improved idle. Also, solved my dieseling problem as I lowered the idle speed.
Anyway, during the teardown we discovered that the harmonic balancer is only a 7 inch balancer. The pro that was helping me said I should have an 8 inch.
I'm dealing with a 1974 block/crank 454 that was transplanted into my '66 coupe.
So, do I need to replace it with the proper 8" balancer or let it go? I'm not racing, if that's an issue.
Thanks in advance for the advice.
Plowboy :cheers:
Team Owner
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From: Washington Michigan
Re: Harmonic Balancer Question (Spankee)
All Corvette 454's used the same 8" counterweighted harmonic damper; don't know if there was a 7" counterweighted balancer or not for other applications, but all 454's require the counterweighted balancer. The only BB Corvette applications that used 7" neutral-balanced dampers were hydraulic-lifter 427's. All 454's MUST use counterweighted dampers AND flywheels/flexplates, as they're externally balanced.
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Joined: Oct 2002
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From: Denver CO
Re: Harmonic Balancer Question (JohnZ)
Thanks.
My guess is that the 454 was a short block rebuild and they took the 427 7" balancer & slapped it on the 454. Too bad the 427block has disappeared but was probably trashed anyway.
I'm thinking I can get by w/ the 7" balancer for now unless I hear anything too negative.
I may put the car back to 'the numbers' eventually. That will depend on the cost vs benefit. For now I'm just enjoying the ride. :cheers:
Plowboy
My guess is that the 454 was a short block rebuild and they took the 427 7" balancer & slapped it on the 454. Too bad the 427block has disappeared but was probably trashed anyway.
I'm thinking I can get by w/ the 7" balancer for now unless I hear anything too negative.
I may put the car back to 'the numbers' eventually. That will depend on the cost vs benefit. For now I'm just enjoying the ride. :cheers:
Plowboy
Burning Brakes
Joined: Nov 2000
Posts: 813
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From: da up
Re: Harmonic Balancer Question (Plowboy)
As already posted
396,402,427 engines are internally balanced and have a neutral balance balancer and flywheel. 454s should use a 454 balancer and flywheel.
otherwise it will vibrate.
396,402,427 engines are internally balanced and have a neutral balance balancer and flywheel. 454s should use a 454 balancer and flywheel.
otherwise it will vibrate.
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Joined: Oct 2000
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From: Washington Michigan
Re: Harmonic Balancer Question (Plowboy)
Make absolutely sure your 7" balancer is counterweighted - you can tell by looking at the rear portion of the inner hub; it will have a thicker edge for about 120 degrees around its inner circumference. If it has a non-counterweighted 427 balancer, you're headed for a possible broken crank. Your 454 NEEDS a counterweighted 8" balancer, and a counterweighted flywheel/flexplate. :yesnod:
Melting Slicks
Joined: Aug 2011
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All Corvette 454's used the same 8" counterweighted harmonic damper; don't know if there was a 7" counterweighted balancer or not for other applications, but all 454's require the counterweighted balancer. The only BB Corvette applications that used 7" neutral-balanced dampers were hydraulic-lifter 427's. All 454's MUST use counterweighted dampers AND flywheels/flexplates, as they're externally balanced.
1973 GM parts book calls out p/n :
3963529 for '70 454 (ex HD) and '71-'72 with High Perf 454
3963530 for '71 with Sp. High Perf 454
330849 for '73-'74 454 Corvette's, '73-'76 Chevrolets, '76-'84 Chevy p/u's (probably '73-'84)
Would you be able to shed light on the three GM part numbered balancers : diameter , width's and weight's ?
I also have a three 454 balancers :
date code :
03474 - stamped 3530H
054 79 - stamped H 3530
348 83 - stamped H3530
Is the H3530 / 3530H stamping the last four digits of the p/n as one usually expects ?
I know GM listed balancer p/n 3963250 in the old "Stopwatch" Book and in the following Chevy Power Books as the recommended balancer for Hi-Po 454 (LS6 LS7) applications.
I find it hard to believe that I may have have three of the Hi-Po 454 balancers ?
I wonder if these may actually be the 330849 regular production line installed units based on the date codes ?
Thank you,
Jerry
Last edited by QIK59; Feb 26, 2020 at 03:14 PM. Reason: p/n error
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Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,926
From: Washington Michigan
Hi John, Sorry to bring up an ancient thread but I have spent the morning trying to find specific info on 454 balancers :
1973 GM parts book calls out p/n :
3963529 for '70 454 (ex HD) and '71-'72 with High Perf 454
3963530 for '71 with Sp. High Perf 454
330849 for '73-'74 454 Corvette's, '73-'76 Chevrolets, '76-'84 Chevy p/u's (probably '73-'84)
Would you be able to shed light on the three GM part numbered balancers : diameter , width's and weight's ?
I also have a three 454 balancers :
date code :
03474 - stamped 3530H
054 79 - stamped H 3530
348 83 - stamped H3530
Is the H3530 / 3530H stamping the last four digits of the p/n as one usually expects ?
I know GM listed balancer p/n 3963250 in the old "Stopwatch" Book and in the following Chevy Power Books as the recommended balancer for Hi-Po 454 (LS6 LS7) applications.
I find it hard to believe that I may have have three of the Hi-Po 454 balancers ?
I wonder if these may actually be the 330849 regular production line installed units based on the date codes ?
Thank you,
Jerry
1973 GM parts book calls out p/n :
3963529 for '70 454 (ex HD) and '71-'72 with High Perf 454
3963530 for '71 with Sp. High Perf 454
330849 for '73-'74 454 Corvette's, '73-'76 Chevrolets, '76-'84 Chevy p/u's (probably '73-'84)
Would you be able to shed light on the three GM part numbered balancers : diameter , width's and weight's ?
I also have a three 454 balancers :
date code :
03474 - stamped 3530H
054 79 - stamped H 3530
348 83 - stamped H3530
Is the H3530 / 3530H stamping the last four digits of the p/n as one usually expects ?
I know GM listed balancer p/n 3963250 in the old "Stopwatch" Book and in the following Chevy Power Books as the recommended balancer for Hi-Po 454 (LS6 LS7) applications.
I find it hard to believe that I may have have three of the Hi-Po 454 balancers ?
I wonder if these may actually be the 330849 regular production line installed units based on the date codes ?
Thank you,
Jerry
Melting Slicks
Joined: Aug 2011
Posts: 3,135
Likes: 261
Thanks much for the reply.
The P&A books just state applications.
Oh well on to other possible resources
Jerry
