LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Snapped Timing chain...WHY??

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Old Jan 27, 2008 | 01:32 PM
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b4cz2896's Avatar
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Snapped Timing chain...WHY??

My 383 procharged stroker motor with just 2000 miles on it snapped the timing chaing yesterday! I cant figure out what happened. Anyone ever snapped one before? I was a new stock setup (crank gear, cam gear and chain). Ill try and get some pics up soon, but i shredded all the teeth of the crank gear ALL 18 TEETH!!
Old Jan 27, 2008 | 01:38 PM
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yes i snapped my timming chain after 30 miles and it was an all new Lunati set up and it sucked and summit would not give me a new one be it was over 90 days and Lunati would not help me so never get a Lunati timming set lol
Old Jan 27, 2008 | 01:42 PM
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Are you running a HV oil pump and thick oil? They can place an additional heavy load on the timing chain.

WD
Old Jan 27, 2008 | 01:43 PM
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Something could have bound up. If you pull the valve covers how does it look? Pray a piston didnt catch a valve when that broke.

How did it break? Were you at WOT? RPM's? And noises before it let lose? Can you turn the crank by hand? If the rockers are loosened, can you spin the cam freely? When you installed the cam, did you check piston to valve clearance?

Also, stepping out on a limb here, but if you take the belts off, do the accessories all turn freely? Including the blower?

DO NOT hit the starter to crank it cause if the pistons hit a valve, your screwed BIG TIME.
Old Jan 27, 2008 | 02:28 PM
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Was it a new one from GM or from Cloyes?
Old Jan 27, 2008 | 03:22 PM
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Oh and if everything checks out that I mentioned, which it probably will, dont rule out faulty parts.

My dad broke the timing chain in his 5.0 F150. Got a new factory replacemnet. It broke 3 weeks later. My Dad knew the guy at parts and he said they had some QC issues and it was definatly a faulty part. Replacement part came free of charge. Except the 2nd time around, we had to do it outside in our driveway in 10* weather lol...
Old Jan 27, 2008 | 04:29 PM
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Also, check the wear pattern on the oil pump 90 degree gear drive and see if it has excessive wear.

WD
Old Jan 27, 2008 | 11:47 PM
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Check your water pump to make sure it is not seized.
That is what caused my chain to snap.
Old Jan 28, 2008 | 06:51 AM
  #9  
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Why skimp out on a stock timing chain with a 383 Procharged setup
Old Jan 28, 2008 | 07:57 AM
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haha yea that's what i was thinking????
Old Jan 28, 2008 | 08:25 AM
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Cause he rolls around with a bunch of shoe-maker racers who are all broke but still want to go fast.

...... chinease parts (junk) cant handle 500+hp hv pump stiff valve springs and ant driving.

HOVERBOARDS DONT WORK ON WATER!!!!!

Last edited by cause4panic; Jan 28, 2008 at 08:39 AM.
Old Jan 29, 2008 | 06:28 AM
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I broke a cloyes and a stock chain on my old 383, both times the motor went back to the machine shop that assembled it and they couldn't find anything wrong. It's been running a few years in another car now with a cloyes double roller without any problems. Both times I destroyed valves though, I think 5 the first time and 6 the second time. No noises, car just shut off at wot around 4500-5000rpms both times, 500 miles on the new motor the first time it broke and about 800 the second time.

I now run only a progear timing chain, nothing else.
Old Jan 30, 2008 | 07:51 PM
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Yes the valves hit the piston on the number 8 and number 3. Water pump spins free. I think it was a defective crank gear that let go first. No noise, i went full throtle and bam the car shut off. So i thought i blew off some intake piping like usual, but when i check every thing was tight. Cranked the car to see if it would fire and nothing. So i pulled a plug wire to see if i was getting spark and i wasnt. Though my new AC delco opti took a crap and towed the car home. Pulled the opti and was turning the crank by hand when i realized that the cam wasnt turning so thats when i started to sweat. Pulled the valve covers and rockers to find 2 or 3 bent valves. The chain broke in two and the crank gear was stripped clean. I did have a high pressure pump with 10w30 oil as per recommended by the engine builder. Im going to be tearing it down this weeked to see what other damage was done. The machine shop said they would take care of what ever needs attention, but im still upset. Its alot of work to pull the motor. I am going to part it out after that so if anyone needs parts from a 96 camaro B4C let me know. Thanks for the input!
Old Jan 31, 2008 | 01:12 PM
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Just curious, why you getting rid of it? I think it'd be worth it for you to keep the car at this point. Your never going to get your money out of it parting it out.
Old Jan 31, 2008 | 11:09 PM
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Time for a new project, and my credit card bills are keeping me up at night.



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