Broken Timing chains...i'm curious..
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
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From: BFE
I broke my stock LS1 timing chain a few years ago while getting on the gas to merge into highway traffic. It happened in the desert halfway between Phoenix and LA with the family on board headed to Disneyland.
The car was a bit rough when I bought it in 2000 - it had been a lease and already had 48k miles on it (I don't think it was well cared for). Fortunately, my extended warranty mostly covered installing a new motor.
Among a lot of other damage (broken pistons, rod, block, and valves), there was a rod with broken bolts. The GM tech was not sure if the chain snapped from the shock of the rod cap coming off or if the snapping chain and resultant shock of valves hitting pistons caused the chain to snap. I think the chain went first but it could have been the rod first.
Steve
The car was a bit rough when I bought it in 2000 - it had been a lease and already had 48k miles on it (I don't think it was well cared for). Fortunately, my extended warranty mostly covered installing a new motor.
Among a lot of other damage (broken pistons, rod, block, and valves), there was a rod with broken bolts. The GM tech was not sure if the chain snapped from the shock of the rod cap coming off or if the snapping chain and resultant shock of valves hitting pistons caused the chain to snap. I think the chain went first but it could have been the rod first.
Steve I have had two stock chains that I have seen broken here at the shop. One was a lower mileage Z06 with a Procharger on board and was run very hard. Still had stock springs at the time. Possibly missed a shift and had piston to valve contact first......definitely after. No other damage besides notched pistons and a few bent valves. Ran fine after a new chain and a few used stock valves.
Second was a higher mileage SS M6 that is also run pretty hard. It was recently gone into and has dual springs with 125lb seat pressure. Nothing too bad. Again, a new chain and cylinder head repair and she should be fine.
Over the past 7-8 years dealing with the LSx engines, these are the only two chain failures I have seen. Most failures, mainly stock chains, I hear of have 140+lbs of seat pressure and run over 6600RPM quite a bit.
Hope this helps.
Mike Norris
Second was a higher mileage SS M6 that is also run pretty hard. It was recently gone into and has dual springs with 125lb seat pressure. Nothing too bad. Again, a new chain and cylinder head repair and she should be fine.
Over the past 7-8 years dealing with the LSx engines, these are the only two chain failures I have seen. Most failures, mainly stock chains, I hear of have 140+lbs of seat pressure and run over 6600RPM quite a bit.
Hope this helps.
Mike Norris
had a JWIS chain with hex-adjust gears in last years motor. 250+ seat pressure, not sure on the open pressure (ISKY springs), shifting at 8k.
Had a lifter explode, still ran, didn't know it was broke actually
Exhaust covered up alot of engine noise.
Chain survived.
Had a lifter explode, still ran, didn't know it was broke actually
Exhaust covered up alot of engine noise.Chain survived.
On my '98 SS the stock timing chain broke when it had 55k miles on it. Running ported heads with a small duration Crane Cam and single springs at the time. I was on the highway and hit the nitrous button at WOT and the motor just died. Pulled over to the side of the road and it, never started again. Had catasrophic damage to all the valves and nice smileys on all the piston tops. Had to tow my car from Florida to Houston. Not good when this happens so far from home.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
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Based on the responses so far, the stock chain looks pretty solid. How would stiffer springs, like many here run, affect overall life since it appears that stouter springs may help bring on its demise. Something like Comp 918's or the Cranes?
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Is the LS2 chain supposed to be stronger than the stock LS1 chain. I plan on running an F11 cam w/patriot dual golds & putting in a new LS2 chain. Wondering if I should get something stronger??
We use the jwis chain also. I have had two broken ones under same basic scenario. Both road race 346's. 1 had lost third gear early in the race (3 hour Motorola cup). Constant driving up past 3900-4100rpm caused by skipping from second to fourth.
2 had 1 lap lead 1 hour into race. They started shifting at 5000 to slow down lap times. This brought them into the same rev zone the engine does not like.
Both chains had multiple locked up kinked links, with one link broken.
After we tested with different durometer rings we found a ring setup that helped to control the bad vibes in that zone.
My turbo engine has this chain with a stock upper gear and a cloyes lower. The springs are 350+ on seat 950 open. The shift point is 8900rpm. So far so good.
Kurt
2 had 1 lap lead 1 hour into race. They started shifting at 5000 to slow down lap times. This brought them into the same rev zone the engine does not like.
Both chains had multiple locked up kinked links, with one link broken.
After we tested with different durometer rings we found a ring setup that helped to control the bad vibes in that zone.
My turbo engine has this chain with a stock upper gear and a cloyes lower. The springs are 350+ on seat 950 open. The shift point is 8900rpm. So far so good.
Kurt