LT4 extreme chain
Thread Starter
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
LT4 extreme chain
Just a quick update to ease some worries. I had a customer and forum members engine apart last week. I had installed a Extreme timing set into this engine some time ago and shipped the engine to So Cal for installation. It came up to my shop for tuning and because of other issues I removed the engine to check the internals out. In the process I inspected the LT4 timing set and found absolutely no signs of abnormal wear on the waterpump drive gear. Of course this engine is near new, but has a few hundred miles on it and several 6500 RPM dyno passes. By the way this engine made over 580 RWHP in 5th gear which peaked at 6000 and held it nearly flat to the test RPM end point of 6500 RPM !
Large Impressive Member
Joined: Jul 2003
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
I'm wondering if some of the problems with these might be due to the front oil gallery plugs being replaced with ones that don't have the holes in them. Also, there was the question of some folks, possibly not using the pump drive gear that comes w/ the ED set. What are your thoughts on this, Tom?
Melting Slicks
Joined: Dec 2000
Posts: 2,719
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From: Fremont Oh
Larryfs,
The point was there was some discussions some time back where the waterpump drive gear was eating up the cam gear on the extreme gear set.
Tom was kind enough to share a update...
Mo
The point was there was some discussions some time back where the waterpump drive gear was eating up the cam gear on the extreme gear set.
Tom was kind enough to share a update...
Mo
Bench Racer
Joined: Feb 2003
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From: Palm Beach Gardens FL
St. Jude '03 thru 14,'25
Originally Posted by larryfs
is there a link to the issues being discussed?
http://forums.corvetteforum.com/show...m_id=48&arch=1
Safety Car
Joined: Dec 2002
Posts: 3,655
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From: Charleston SC
I just read somthing interesting in another thread. Mo Brandy stated that if you put a SBC double roller chain in an LT4 you need to add a .10 shim to compinsate for the reluctor ring being removed. Is it possibble that the LT4 ED set is .10 thiner then the LT1 set? If so perhaps this is the source of the problem, just a thought that could be chacked rather quick with a digital caliper if someone had both timing sets.
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Safety Car
Joined: Sep 2002
Posts: 4,030
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From: Maryland
Originally Posted by tjwong
In the process I inspected the LT4 timing set and found absolutely no signs of abnormal wear on the waterpump drive gear. !
How was the water pump itself? Mine hardly turns. I could NOT turn it by hand the other day at all grabbing the splined shaft. Taking the screws out and touching the impeller--now I can turn it. But it's tight-tight-tight.
The metal shards in the pressed in waterpump gear bearing also have locked it up--hard to turn it and it's not smooth.
So I stand by my Conclusion--bad water pump bearing by *** of Canada. At high rpm (5000) it wore the ED cam sproket enough to send shard into the bearing of the WP gear drive and then both accelerated the wear & shard production.
This explains why it is a rare issue--only LT4's or ED sets will be affected and only if you happen to get a bad waterpump (a new one--probably have let quality slip as with the Clutch slave Cylinder's and Opti's). And the bad waterpump in mine didn't show itself for 15,000 mi and there were plenty of drag passes and 4 track days in those miles, along with 3 high rpm dyno passes. The bearing just didn't last, it was ok for a while.
Last edited by sothpaw2; Feb 27, 2006 at 12:07 PM.
Safety Car
Joined: Sep 2002
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From: Maryland
Originally Posted by Corvette Kid NC
I'm wondering if some of the problems with these might be due to the front oil gallery plugs being replaced with ones that don't have the holes in them. Also, there was the question of some folks, possibly not using the pump drive gear that comes w/ the ED set. What are your thoughts on this, Tom?
2 Folks on this forum, myself and Michael (MSR), had the correct LT1 oil plug with the hole and we both had the same problem with the Cam sprocket wearing itself to death. Mine was a stock, untouched shortblock.
Also, I can confirm (because I have the pieces now) that my car certainly had the ED wp gear on it--the entire ED set was installed as called for. This was also the case with MSR if I recall.
Le Mans Master
Joined: Feb 1999
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From: South Carolina
St. Jude Donor '03 & '05
Originally Posted by FD2BLK
I just read somthing interesting in another thread. Mo Brandy stated that if you put a SBC double roller chain in an LT4 you need to add a .10 shim to compinsate for the reluctor ring being removed. Is it possibble that the LT4 ED set is .10 thiner then the LT1 set? If so perhaps this is the source of the problem, just a thought that could be chacked rather quick with a digital caliper if someone had both timing sets.
Thread Starter
Le Mans Master
Joined: Jan 2003
Posts: 8,596
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From: Portland Oregon
Originally Posted by Mo_Bandy
Way to go Tom!
Everything is sorted out on it now?
Mo
Everything is sorted out on it now?
Mo
Melting Slicks
Joined: Dec 2000
Posts: 2,719
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From: Fremont Oh
Originally Posted by FD2BLK
I just read somthing interesting in another thread. Mo Brandy stated that if you put a SBC double roller chain in an LT4 you need to add a .10 shim to compinsate for the reluctor ring being removed. Is it possibble that the LT4 ED set is .10 thiner then the LT1 set? If so perhaps this is the source of the problem, just a thought that could be chacked rather quick with a digital caliper if someone had both timing sets.
I responded to this in the other thread as well but for those here. I clarified that the crank gear is the same depth, the difference is in the crank hub, this is only on the 96's I beleive as the 95's did not have the reluctor wheel on them..
I would agree as posted previously that it is probably more a function of a waterpump seize than that of the timing set... my personal opinion...
Mo
