harmonic balancer question........
Thread Starter
Race Director
Joined: Mar 2009
Posts: 19,777
Likes: 4,592
From: Canada's capital
2020 Corvette of the Year Finalist (appearance mods)
C1 of Year Finalist (appearance mods) 2019
harmonic balancer question........
Is there a way to tell by looking at a balancer, off the car, if it's slipped on the hub or has deteriorated to the point where it needs to be rebuilt?
Thanks.
Thanks.
Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,926
From: Washington Michigan
Le Mans Master
Joined: Nov 2008
Posts: 5,691
Likes: 12
From: columbus oh
john is correct but there were some years in the seventies where the mark did not line up with the index key....we are talkin' small blocks here.....they moved the timing tab up and had to move the mark for timing light purposes....
Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,926
From: Washington Michigan
Le Mans Master
Joined: Nov 2008
Posts: 5,691
Likes: 12
From: columbus oh
That happened in 1969 when the passenger cars went to the "long" water pump and passenger-side alternator mounting; the timing index line was moved 10* counter-clockwise on the weight, and the timing tabs on the timing cover moved to match. However, the Corvette didn't change - it stayed with the "short" water pump and timing index line directly aligned with the hub keyway.
Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,926
From: Washington Michigan
i have worked on numerous corvette small blocks built in the seventies john, and yes, my good friends 77 corvette indeed had a balancer keyed with the timing mark not aligned with the index keyway and a higher placed timing tab and indeed it was the original motor since he bought it brand new, also the engine was painted blue from the factory.....
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
Since it is highly probable that any SBC has been rebuilt or modified, it is always best to find TDC anew. Of the two harmonic dampers I've commonly found, the TDC mark is either inline with the keyway or 10 degrees CCW. If it is not at either, I reject the HD.
Thread Starter
Race Director
Joined: Mar 2009
Posts: 19,777
Likes: 4,592
From: Canada's capital
2020 Corvette of the Year Finalist (appearance mods)
C1 of Year Finalist (appearance mods) 2019
that's great info Frank and John. Can you tell by looking at the rubber between inner and outer ring if it has deteriorated?
This balance was bought used, an 8 in, so I don't know what it's off off or year. So I take it it's either lined up or 10 degrees off to the left from the front, right? Anything else means it's slipped and useless?
edit: OK so I have one 8 in. and the line is approx 5/8th of an inch to the left, and a 7 in. that's lined up perfectly. Are they both good?
This balance was bought used, an 8 in, so I don't know what it's off off or year. So I take it it's either lined up or 10 degrees off to the left from the front, right? Anything else means it's slipped and useless?
edit: OK so I have one 8 in. and the line is approx 5/8th of an inch to the left, and a 7 in. that's lined up perfectly. Are they both good?
Last edited by Kerrmudgeon; Aug 6, 2012 at 04:56 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Le Mans Master
Joined: Nov 2008
Posts: 5,691
Likes: 12
From: columbus oh
that's great info Frank and John. Can you tell by looking at the rubber between inner and outer ring if it has deteriorated?
This balance was bought used, an 8 in, so I don't know what it's off off or year. So I take it it's either lined up or 10 degrees off to the left from the front, right? Anything else means it's slipped and useless?
edit: OK so I have one 8 in. and the line is approx 5/8th of an inch to the left, and a 7 in. that's lined up perfectly. Are they both good?
This balance was bought used, an 8 in, so I don't know what it's off off or year. So I take it it's either lined up or 10 degrees off to the left from the front, right? Anything else means it's slipped and useless?
edit: OK so I have one 8 in. and the line is approx 5/8th of an inch to the left, and a 7 in. that's lined up perfectly. Are they both good?
Thread Starter
Race Director
Joined: Mar 2009
Posts: 19,777
Likes: 4,592
From: Canada's capital
2020 Corvette of the Year Finalist (appearance mods)
C1 of Year Finalist (appearance mods) 2019
So 10 degrees isn't 5/8ths of an inch then I take it? No idea what it's from or year. Part #3898966, and 213 79 and H2222 on the flip side.
Le Mans Master
Joined: Nov 2008
Posts: 5,691
Likes: 12
From: columbus oh
the timing covers are different also...the tab is mounted a lot higher than the usual standard one...good luck...
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
that's great info Frank and John. Can you tell by looking at the rubber between inner and outer ring if it has deteriorated?
This balance was bought used, an 8 in, so I don't know what it's off off or year. So I take it it's either lined up or 10 degrees off to the left from the front, right? Anything else means it's slipped and useless?
edit: OK so I have one 8 in. and the line is approx 5/8th of an inch to the left, and a 7 in. that's lined up perfectly. Are they both good?
This balance was bought used, an 8 in, so I don't know what it's off off or year. So I take it it's either lined up or 10 degrees off to the left from the front, right? Anything else means it's slipped and useless?
edit: OK so I have one 8 in. and the line is approx 5/8th of an inch to the left, and a 7 in. that's lined up perfectly. Are they both good?
Also, I'm pretty sure the '79 C 10 truck I had, the timing pointer was at 12:00. Straight up at the top and the timing cover pointer was like a piece of round tubing that you shot the light through to set timing.
Thread Starter
Race Director
Joined: Mar 2009
Posts: 19,777
Likes: 4,592
From: Canada's capital
2020 Corvette of the Year Finalist (appearance mods)
C1 of Year Finalist (appearance mods) 2019
So the math works out to .71 is 10 degrees, and that's around 5/8th of an inch, so it looks like it's good. Now, the rubber shows tiny hairline cracks going around the perimeter.....is that normal?
Last edited by Kerrmudgeon; Aug 6, 2012 at 06:20 PM.
Race Director
Joined: Jun 2006
Posts: 17,901
Likes: 751
From: Inverness FL
St. Jude Donor '07
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
Thread Starter
Race Director
Joined: Mar 2009
Posts: 19,777
Likes: 4,592
From: Canada's capital
2020 Corvette of the Year Finalist (appearance mods)
C1 of Year Finalist (appearance mods) 2019
