72 LT1 harmonic balancer
Thread Starter
Burning Brakes
Joined: Sep 2010
Posts: 799
Likes: 26
From: Lexington Park Maryland
72 LT1 harmonic balancer
Rebuilt the engine 5k ago, at the time the harmonic balancer looked good. Now I see a sign of oil leak, it is coming from the front of the engine. I assess it is the from the seal or maybe the harmonic balancer has a grove.
Will an OEM direct replacement from a local part store will work or does it have to be a performance version since this is an LT1. The engine is stock, no added performance parts added to it.
Will an OEM direct replacement from a local part store will work or does it have to be a performance version since this is an LT1. The engine is stock, no added performance parts added to it.
Melting Slicks
Joined: Mar 2006
Posts: 3,456
Likes: 102
From: Piedmont Va
St. Jude Donor '11-'12-'13,'19-'20
If you are leaking engine oil from behind the HB the issue is most likely the front seal. Need to pull HB, timing chain cover and oil pan and replace the gaskets and front seal would be likely fix. You can inspect the balancer while it's off. Good luck!
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
If your balancer is grooved there are repair sleeves avalible to give a new surface for the seal to ride on. Visit a local auto machine shop with your balancer in hand it should be under $50 to have them repair it.....the sleeve is pretty inexpensive but, installation of the part can be tricky. The same machine shop should be a cheap source for a new seal.
Last edited by Solid LT1; May 10, 2016 at 12:45 PM.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
The old Speedy Sleeves for the the harmonic balancer were much too tight of a tolerance....they were very tricky to install.....in years of late though....this has changed....they press right on in a vice with a block of wood. Make sure you use green machinists loc-tite when installing as it lubricates for the install and holds it taught when dry...
For all this work though.....I would never put an old balancer back on....the rubber between the inner and outer shell....
Either get a quality reproduction or an aftermarket unit with timing marks on it......
Remember to remove a timing cover on a small block correctly...the oil pan must be removed.....
Good luck!
Jebby
For all this work though.....I would never put an old balancer back on....the rubber between the inner and outer shell....
Either get a quality reproduction or an aftermarket unit with timing marks on it......
Remember to remove a timing cover on a small block correctly...the oil pan must be removed.....
Good luck!
Jebby
Burning Brakes
Joined: Apr 2008
Posts: 1,222
Likes: 93
From: shelbyville West Michigan
I agree with Jebby, would replace an old balancer instead of sleeving. back in the day, I sold lots of the fel-pro sleeve's, but back then we did not see the rubber bonding failures like we do today. a 10-15 yo balancer is still generally good, but when they get to 25+ yrs. on them it's a different story.
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
The LT-1 has a "special" dampener from GM.....it is thicker than the regular "Impala Station Wagon" 350 motor's dampener. There are people capable of rebuilding balancers.
This is the place I send my work to.....
http://damperdoctor.com/index.php?route=common/home
Thinking about this.....there is also the potential you have a leak from the internal side of the balancer.....use some RTV or Halomar sealant on the crank key/balancer bore areas when reinstalling....even though the balancer to crank fit should be a forced fit, I have seen leakage from crank area before without sealant done to this junction.
This is the place I send my work to.....
http://damperdoctor.com/index.php?route=common/home
Thinking about this.....there is also the potential you have a leak from the internal side of the balancer.....use some RTV or Halomar sealant on the crank key/balancer bore areas when reinstalling....even though the balancer to crank fit should be a forced fit, I have seen leakage from crank area before without sealant done to this junction.
Last edited by Solid LT1; May 12, 2016 at 11:29 AM.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Any high performance balancer is a better choice than the original.....unless of course originality is concerned.
Plus it will have real timing marks on it. I do not use dial back timing lights as I seen as much as two degrees discrepancy through a MSD box to true timing.
Of course...if the engine is balanced properly to begin with...the balancer is not such a critical part anyhoo.....
I like to run as small of a balancer as possible on a professionally balanced engine.
I have a 6.750 on my 406......it is a Professional Products parts.....used them for many years with no issues.
If you are racing and see extended 6500+ rpm.....step up to an ATI....they are rebuildable at home. Pricey...but worth it.
Pioneer also makes quality stock replacements that appear very close to an original for around $100.
Jebby
Plus it will have real timing marks on it. I do not use dial back timing lights as I seen as much as two degrees discrepancy through a MSD box to true timing.
Of course...if the engine is balanced properly to begin with...the balancer is not such a critical part anyhoo.....
I like to run as small of a balancer as possible on a professionally balanced engine.
I have a 6.750 on my 406......it is a Professional Products parts.....used them for many years with no issues.
If you are racing and see extended 6500+ rpm.....step up to an ATI....they are rebuildable at home. Pricey...but worth it.
Pioneer also makes quality stock replacements that appear very close to an original for around $100.
Jebby
Thread Starter
Burning Brakes
Joined: Sep 2010
Posts: 799
Likes: 26
From: Lexington Park Maryland
Any high performance balancer is a better choice than the original.....unless of course originality is concerned.
Plus it will have real timing marks on it. I do not use dial back timing lights as I seen as much as two degrees discrepancy through a MSD box to true timing.
Of course...if the engine is balanced properly to begin with...the balancer is not such a critical part anyhoo.....
I like to run as small of a balancer as possible on a professionally balanced engine.
I have a 6.750 on my 406......it is a Professional Products parts.....used them for many years with no issues.
If you are racing and see extended 6500+ rpm.....step up to an ATI....they are rebuildable at home. Pricey...but worth it.
Pioneer also makes quality stock replacements that appear very close to an original for around $100.
Jebby
Plus it will have real timing marks on it. I do not use dial back timing lights as I seen as much as two degrees discrepancy through a MSD box to true timing.
Of course...if the engine is balanced properly to begin with...the balancer is not such a critical part anyhoo.....
I like to run as small of a balancer as possible on a professionally balanced engine.
I have a 6.750 on my 406......it is a Professional Products parts.....used them for many years with no issues.
If you are racing and see extended 6500+ rpm.....step up to an ATI....they are rebuildable at home. Pricey...but worth it.
Pioneer also makes quality stock replacements that appear very close to an original for around $100.
Jebby
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Le Mans Master
Joined: Oct 2010
Posts: 6,936
Likes: 848
From: melbourne florida
2023 C3 of the Year Finalist - Modified
The 350/350 LT-1 and the L-82 all used the 8 inch balancer as the engines were internally balanced.get at least a stock replacement,,something like an ATI is great,
Melting Slicks
Joined: Oct 2001
Posts: 2,065
Likes: 1,395
From: Halifax, Nova Scotia, Canada
A ZZ4 crate engine balancer is an exact replacement for the old 350/350, LT-1 balancer. Only difference is the ZZ4 balancer has some additional degree markings.