broken timing chain
Thread Starter
Drifting
Joined: Dec 1999
Posts: 1,541
Likes: 2
From: Raleigh NC
broken timing chain
UPDATE: It happened again. This time it was a double rollmaster. ~2000 miles and 14 track days. It happened yesterday at the track while in 4th turning about 5200 rpms. When I was supercharged my cam bolts loosened while at that track. My thought now is that maybe that trashed the front cam bearing. This sucks. This time I’ll fix it with a new motor.
My LS2 timing chain broke last night. Last year with a Mag SC my stock cam bolts backed out. I replaced the top gear and chain with new LS2 stuff. I pulled the S/C a few months later and did a H/C. AFR 205s and a 228/232. I might have 1000 miles on the H/C and no more than 3k on the timing chain but I do have 4 days of HPDEs on the chain and 2 days with the H/C. On the way home last night I pulled away from a light, shifted to second and opened it up. At about 5k rpms the chain let go. I pulled the passenger side head and http://i293.photobucket.com/albums/m...e/IMG_0777.jpg is the worst piston. Can I put my old heads on and get some driving time in? The AFRs have 4 bent valves. I'll be sending them back to Tony for a look over.
Thanks
Rob
My LS2 timing chain broke last night. Last year with a Mag SC my stock cam bolts backed out. I replaced the top gear and chain with new LS2 stuff. I pulled the S/C a few months later and did a H/C. AFR 205s and a 228/232. I might have 1000 miles on the H/C and no more than 3k on the timing chain but I do have 4 days of HPDEs on the chain and 2 days with the H/C. On the way home last night I pulled away from a light, shifted to second and opened it up. At about 5k rpms the chain let go. I pulled the passenger side head and http://i293.photobucket.com/albums/m...e/IMG_0777.jpg is the worst piston. Can I put my old heads on and get some driving time in? The AFRs have 4 bent valves. I'll be sending them back to Tony for a look over.
Thanks
Rob
Last edited by Rob's 73; Nov 3, 2008 at 07:38 AM.
Le Mans Master
Joined: Dec 2003
Posts: 5,561
Likes: 448
From: Atlanta metro Ga.
My LS2 timing chain broke last night. Last year with a Mag SC my stock cam bolts backed out. I replaced the top gear and chain with new LS2 stuff. I pulled the S/C a few months later and did a H/C. AFR 205s and a 228/232. I might have 1000 miles on the H/C and no more than 3k on the timing chain but I do have 4 days of HPDEs on the chain and 2 days with the H/C. On the way home last night I pulled away from a light, shifted to second and opened it up. At about 5k rpms the chain let go. I pulled the passenger side head and http://i293.photobucket.com/albums/m...e/IMG_0777.jpg is the worst piston. Can I put my old heads on and get some driving time in? The AFRs have 4 bent valves. I'll be sending them back to Tony for a look over.
Thanks
Rob
Thanks
Rob
Melting Slicks
Joined: May 2005
Posts: 3,394
Likes: 12
From: Leon Iowa
St. Jude Donor '06-'07-'08-'09
A buddy of mine done a cam swap on his LS1 trans am, well he didn't get the timing correct so it had a bad knock. It was the valves hitting the pistons. looked just like yours. I replaced the bent valves and put the heads back on and it's been running for over a year with no problems. I told him now he can get a bigger cam since the flycutting is already done for him.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Ive seen the same damage before and once the valves were replaced,,, the car ran just as good as before. I would smooth off any rough surfaces and edges on the top of the piston where the damage occured and call it a good day!
You should be good to go!
You should be good to go!
Thread Starter
Drifting
Joined: Dec 1999
Posts: 1,541
Likes: 2
From: Raleigh NC
Thanks for the replies. I don't think I will have an opportunity to go to the track until mid-June so I think I will see if I can get the AFRs repaired before then. I'll get the drivers side head off tonight. Hopefully there is nothing worse on that side. I'll post an update.
Thanks
Rob
Thanks
Rob
Heel & Toe
Joined: Jan 2008
Posts: 21
Likes: 0
From: Oak Hill Virginia
This is Rob's 73. I'm on my wife's laptop and her login.
Here are some pics from the drivers side
http://s293.photobucket.com/albums/m...t=IMG_0782.jpg
http://s293.photobucket.com/albums/m...t=IMG_0785.jpg
http://s293.photobucket.com/albums/m...t=IMG_0788.jpg
http://s293.photobucket.com/albums/m...t=IMG_0790.jpg
What do you guys think. Put the heads on and go?
Please take a look at the one picture of the head and notice the color of the one spark plug. It's very black. Is that a sign of a bad injector. Maybe that's where my 10-15 hp went. I only dyno'd 428/391 with AFRs, 228/232, LTs and underdrive pully.
Thanks for the help
Rob
Here are some pics from the drivers side
http://s293.photobucket.com/albums/m...t=IMG_0782.jpg
http://s293.photobucket.com/albums/m...t=IMG_0785.jpg
http://s293.photobucket.com/albums/m...t=IMG_0788.jpg
http://s293.photobucket.com/albums/m...t=IMG_0790.jpg
What do you guys think. Put the heads on and go?
Please take a look at the one picture of the head and notice the color of the one spark plug. It's very black. Is that a sign of a bad injector. Maybe that's where my 10-15 hp went. I only dyno'd 428/391 with AFRs, 228/232, LTs and underdrive pully.
Thanks for the help
Rob
Last edited by GO-CAR-GO; Apr 17, 2008 at 09:39 PM.
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Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
This is Rob's 73. I'm on my wife's laptop and her login.
Here are some pics from the drivers side
http://s293.photobucket.com/albums/m...t=IMG_0782.jpg
http://s293.photobucket.com/albums/m...t=IMG_0785.jpg
http://s293.photobucket.com/albums/m...t=IMG_0788.jpg
http://s293.photobucket.com/albums/m...t=IMG_0790.jpg
What do you guys think. Put the heads on and go?
Please take a look at the one picture of the head and notice the color of the one spark plug. It's very black. Is that a sign of a bad injector. Maybe that's where my 10-15 hp went. I only don't 428/391 with AFRs, 228/232, LTs and underdrive pully.
Thanks for the help
Rob
Here are some pics from the drivers side
http://s293.photobucket.com/albums/m...t=IMG_0782.jpg
http://s293.photobucket.com/albums/m...t=IMG_0785.jpg
http://s293.photobucket.com/albums/m...t=IMG_0788.jpg
http://s293.photobucket.com/albums/m...t=IMG_0790.jpg
What do you guys think. Put the heads on and go?
Please take a look at the one picture of the head and notice the color of the one spark plug. It's very black. Is that a sign of a bad injector. Maybe that's where my 10-15 hp went. I only don't 428/391 with AFRs, 228/232, LTs and underdrive pully.
Thanks for the help
Rob
I strongly recommend checking the valves for being bent. If there bent even slightly, they wont seal and you will loose compression. A quick check is to clean up the heads and mix up some 50/50 antifreeze/water and poor the water in the combustion chambers with the heads flipped up side down. If you get any water leakage in the intake or exhaust ports, there bad. (remember,,,,thats a quick check
)The real way to check them is a dial indicator and some V blocks.
The pistons are probably fine. Just smooth any sharp edges.
BC
Race Director
Joined: Dec 2004
Posts: 13,760
Likes: 75
From: Haymarket VA
Looks like minimal damage. You got lucky. Depending on the combustion chamber volume you should be able to slap your stock heads back on and roll while the AFR's are being redone.
Good luck,
Kevin
Good luck,
Kevin
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Racer
Joined: May 2007
Posts: 270
Likes: 0
From: Spokane WA
Second thread this week with LS2 timing chain problems. GM quality issues or are they NOT the hot set-up for the LS1/6 motors anymore?
http://forums.corvetteforum.com/show...2+timing+chain
http://forums.corvetteforum.com/show...2+timing+chain
Last edited by Mac11; Apr 19, 2008 at 08:12 AM.
Thread Starter
Drifting
Joined: Dec 1999
Posts: 1,541
Likes: 2
From: Raleigh NC
Actually that is number 5 and that cylinder suffered no damage. Number 6 suffered no damage either. All other cylinders have at least one bent valve. I'm going to just replace the one injector and all valves that have the slightest bit of a witness mark on them or the corresponding piston. I'll bolt the heads back on and do a leak down test. Of course I will smooth out any edges on the pistons.
Any body have a link for a leak down test? I did one on my old 73 once but I forgot exactly how to do it.
Hopefully the motor will hold together until this winter. Scoggin Dicky has 427 short blocks for $4900.
Anybody have a good source for the timing chain dampner? Can you order one from the dealer?
Any body have a link for a leak down test? I did one on my old 73 once but I forgot exactly how to do it.
Hopefully the motor will hold together until this winter. Scoggin Dicky has 427 short blocks for $4900.
Anybody have a good source for the timing chain dampner? Can you order one from the dealer?
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Rob
Not all C5 LS blocks have the machining work incorporated to install the timing chain damper. I was going to drill and tap mine but,,,when I removed the front cover,,,, ,,,,the machined holes were there.
I got mine form Gene Culley at WWW.GMPARTSHOUSE.COM
Hope you have the machined holes too!!
BC
Bill
Not all C5 LS blocks have the machining work incorporated to install the timing chain damper. I was going to drill and tap mine but,,,when I removed the front cover,,,,
,,,,the machined holes were there.I got mine form Gene Culley at WWW.GMPARTSHOUSE.COM
Hope you have the machined holes too!!
BC
Bill
Former Vendor
Joined: Jan 2006
Posts: 128
Likes: 0
Anybody have a good source for the timing chain dampner? Can you order one from the dealer?
We also have our Iwis timing chains in stock for $42.95
Brian
Last edited by bg-sdpc; Apr 21, 2008 at 11:00 AM.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Rob
The new cool stuff will trickel down to our OLDER engines
as soon as someone see
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$
Am I NOT correct?
BC
The new cool stuff will trickel down to our OLDER engines
as soon as someone see$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$
Am I NOT correct?
BC