Calling those w/ broken timing chain experience
Thread Starter
Burning Brakes
Joined: Sep 2001
Posts: 1,173
Likes: 1
From: Aguila AZ
Calling those w/ broken timing chain experience
I found that a broken timing chain is the cause of my instant shut down while on the road race track. I have 6cc valve reliefs in my pistons, AFR heads w/2.08 intake valves and a 250/.612 cam... I cannot compression test the engine until I get a new (LS2) timing chain on the engine. What are the chances that I have bent valves?
Please, only those with actual timing chain failures or first hand experience need to reply.
Shirl
Please, only those with actual timing chain failures or first hand experience need to reply.
Shirl
Le Mans Master
Joined: Jul 2002
Posts: 7,370
Likes: 8
From: Slave to the evil empire
Cruise-In V Veteran
St. Jude Donor '04
Forum member Subdriver had this problem on his T-1 car, do a search and PM him because I believe he had several bent valves but the pistons were alright ...and goodluck 
Former Vendor
Joined: Feb 2004
Posts: 9,615
Likes: 13
From: Burlington NC
Chances are you killed a few valves anyways. I like the idea of pulling the valve covers and see if they are all in a row or not, this will give you a idea. Every timing chain failure has resulted in major problems.
Randy
Randy
Drifting
Joined: Oct 2004
Posts: 1,384
Likes: 8
From: Southwest Virginia
Originally Posted by Randy@DRM
Chances are you killed a few valves anyways. I like the idea of pulling the valve covers and see if they are all in a row or not, this will give you a idea. Every timing chain failure has resulted in major problems.
Randy
Randy
With these high compression heads (small combustion cambers) and that huge cam my guess there is no way those big valves survived!
There if very little room in there when the pistons comes up! You can pop the rockers and do a leak down test without the chain installed. That will tell you real quick if you have problems. I would do a leak down over a compression test anyway. If you have a valve that is very slightly bent it may not show up on compression test but will burn later if not replaced.Good luck
Thread Starter
Burning Brakes
Joined: Sep 2001
Posts: 1,173
Likes: 1
From: Aguila AZ
Well, I threw on an old LS1 chain which allowed me to do a compression check on the engine. The result was; 3 were 100%, 4 were 90%, and one was 60%. That mandated a head removal. Once I got the heads off there was no serious damage. I could see where some of the valves had marked the pistons but the valve reliefs were at the exact angle of the valves and so there was very little interfearance and no bending moment imposed on the valves. The chamber that was low had both valves in contact. I leak checked the valves using gas in the ports and I got minor valve weeping from the low cylinders.
I will now regrind the valves and lap the seats and that will take care of the top end. I don't think I will need to replace any valves. I guess my only option with an LS2 block is to put another LS2 timing chain in the engine and hope it doesn't fail... Wish there was a double roller option for these engines.
I consider myself very lucky to have only this much damage.
Shirl
I will now regrind the valves and lap the seats and that will take care of the top end. I don't think I will need to replace any valves. I guess my only option with an LS2 block is to put another LS2 timing chain in the engine and hope it doesn't fail... Wish there was a double roller option for these engines.
I consider myself very lucky to have only this much damage.
Shirl
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
How about the Katech timing chain. Also, did you install the damper on the timing chain? (Not sure of your setup).
I would also verify that the valve stems are straight prior to lapping.
I would also verify that the valve stems are straight prior to lapping.
Premium Supporting Vendor
Joined: Oct 2005
Posts: 13,975
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From: Clinton Township MI
C7 of Year Finalist (track prepared) 2019
Originally Posted by vettenuts
How about the Katech timing chain. Also, did you install the damper on the timing chain? (Not sure of your setup).
I would also verify that the valve stems are straight prior to lapping.
I would also verify that the valve stems are straight prior to lapping.
We have one on ebay now http://cgi.ebay.com/ebaymotors/ws/eB...e=STRK:MESE:IT never broken (root cause of failure) in all of our C5R racing and durability testing.
Thanks
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Premium Supporting Vendor
Joined: Aug 2001
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From: King George VA
Originally Posted by FFR-Z06
Forum member Subdriver had this problem on his T-1 car, do a search and PM him because I believe he had several bent valves but the pistons were alright ...and goodluck
I did take the valve cover off to verify the timing chain had parted. In my case, I lost six valves, but everything else was okay - I think I was lucky. I bought new valves, had a valve job done on the heads and had it put back together and ran the rest of the season on the motor (winning the 2004 SCCA Midwest Div title on that motor) - but then killed it when the harmonic balancer came off during the Runoffs.
I highly recommend putting the damper and running a heavy duty chain on any motor running over stock rpm limits.
From the 2004 GM Performance Parts Catalog: page 106:
88958607 Timing Chain Damper, LS1, LS6
“This timing chain damper is intended for high engine speed applications and is used to improve timing chain life. Some blocks require drilling and tapping- an instruction sheet is included."
I believe the GM heavy duty chain is GM PART #88958608.
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C66 Racing #66 NASA ST2, SCCA T2
AMSOIL Dealer (Forum Vendor)
AMSOIL Preferred Customer Program (Members buy at Wholesale - a savings of about 25%)
Premium Supporting Vendor
Joined: Aug 2001
Posts: 5,364
Likes: 38
From: King George VA
Originally Posted by Bill Curlee
I'm about to pull the trigger on all of this stuff!! Where is the best place to purchase the chain damper and how much was it??
Thanks
BC
Thanks
BC
GM PART # 88958607
CATEGORY: Belt or Chain, Engine Timing
PACK QTY: 1 CORE CHARGE: $0.00
GM LIST: $120.23
OUR PRICE: $84.16
DESCRIPTION: DAMPENER
GM PART # 88958608
CATEGORY: Belt or Chain, Engine Timing
PACK QTY: 1 CORE CHARGE: $0.00
GM LIST: $109.78
OUR PRICE: $76.84
DESCRIPTION: CHAIN
I've bought from them many times with good luck, but their shipping is normally very high, especially for one part. I'd also check with forum vendor Fred Beans:
Fred Beans Buick Pontiac GMC
Parts Manager: Gene Culley
610-495-1700
E-Mail: gculley@fredbeans.com
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
I needed mine quickly, the only place that had it in stock was Thunder Racing and when I talked to him (soon after the hurricane and UPS was struggling) he personally walked to the stock area, put it in a box and gave it to the postman for a two day delivery that cost me under $4.
The Katech chains is also sold by Thunder Racing (JWIS), it is killer
The Katech chains is also sold by Thunder Racing (JWIS), it is killer