Too much boost and valve float?
Thread Starter
Safety Car
Joined: Mar 1999
Posts: 3,612
Likes: 182
From: Toronto, Canada
Too much boost and valve float?
Last month my motor went kaboom! I pulled all the plugs and the #8 was seriously damaged, the electrode was bent and the plug was banged up. Pulled the valve cover and no broken springs. Fast forward to today and after pulling everything apart this is what was discovered.
Removing the manifold we found the intake valve upstream in the intake runner!
How the heck did that get there?
Removed the passenger side head and you could see most of the valves made contact with the pistons. Pulled the other head off as well with the same reults. This looks like the timing chain has left the building! Sure enough get to the front of the motor and the chain is in the pan!
Here is the #8 piston
Here is the cylinder head.
Good news is the block is fine and will be built with a forged rod and piston.
Who wants to take a stab at what exactly happened?
Removing the manifold we found the intake valve upstream in the intake runner!
How the heck did that get there?
Removed the passenger side head and you could see most of the valves made contact with the pistons. Pulled the other head off as well with the same reults. This looks like the timing chain has left the building! Sure enough get to the front of the motor and the chain is in the pan!
Here is the #8 piston
Here is the cylinder head.
Good news is the block is fine and will be built with a forged rod and piston.
Who wants to take a stab at what exactly happened?
Team Owner
Joined: May 2006
Posts: 21,473
Likes: 356
From: Palmdale, Ca----- 2009 Cyber Gray 4LT A6 F55 452 RWHP 422 RWTQ- RIP 1998 C5 734 RWHP & 585 RWTQ-----
It certainly looks like your spring broke as well as the retainers and dropped the valve into the cylinder!
I first thought it might of been a lean condition with the talk of spark plug electrod - But after the carnage shots it sure seems to be faulty springs!
Did the spring crack or is it intact? if intact I would suspect the retainers, that they broke and let loose the valve and then it got spit up into the intake
Thanks,Matt
I first thought it might of been a lean condition with the talk of spark plug electrod - But after the carnage shots it sure seems to be faulty springs!
Did the spring crack or is it intact? if intact I would suspect the retainers, that they broke and let loose the valve and then it got spit up into the intake
Thanks,Matt
Former Vendor
Joined: Mar 2008
Posts: 2,279
Likes: 1
You should see my new valve springs Bobby, good for .700 lift and they drop right in with no machining. I'll need them with my new cam-it has
.650 lift
But seriously if the timing chain is the oil pan, then it probably let go when you made a trip to the rev limiter.
.650 lift
But seriously if the timing chain is the oil pan, then it probably let go when you made a trip to the rev limiter.
Melting Slicks
Joined: Feb 2006
Posts: 2,184
Likes: 2
Last month my motor went kaboom! I pulled all the plugs and the #8 was seriously damaged, the electrode was bent and the plug was banged up. Pulled the valve cover and no broken springs. Fast forward to today and after pulling everything apart this is what was discovered.
Removing the manifold we found the intake valve upstream in the intake runner!
How the heck did that get there?
Removed the passenger side head and you could see most of the valves made contact with the pistons. Pulled the other head off as well with the same reults. This looks like the timing chain has left the building! Sure enough get to the front of the motor and the chain is in the pan!
Here is the #8 piston
Here is the cylinder head.
Good news is the block is fine and will be built with a forged rod and piston.
Who wants to take a stab at what exactly happened?
Removing the manifold we found the intake valve upstream in the intake runner!
How the heck did that get there?
Removed the passenger side head and you could see most of the valves made contact with the pistons. Pulled the other head off as well with the same reults. This looks like the timing chain has left the building! Sure enough get to the front of the motor and the chain is in the pan!
Here is the #8 piston
Here is the cylinder head.
Good news is the block is fine and will be built with a forged rod and piston.
Who wants to take a stab at what exactly happened?
How much power were you making to snap the chain?
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Thread Starter
Safety Car
Joined: Mar 1999
Posts: 3,612
Likes: 182
From: Toronto, Canada
Race Director
Joined: May 2005
Posts: 15,960
Likes: 21
From: West Norriton PA
St. Jude Donor '08
The LS motor timing chains are pretty slack and sloppy, what did the chain and gears look like ?
Melting Slicks
Joined: Feb 2006
Posts: 2,184
Likes: 2
Thread Starter
Safety Car
Joined: Mar 1999
Posts: 3,612
Likes: 182
From: Toronto, Canada
8000 miles! Completely stock LS6 motor and no bouncing off the rev limiter. I was 3rd gear at about 4500 rpms and I went wot and at about 5300-5500 rpms the engine went boom! Car shut off and I coasted to the side of the road. I tried to start it and would turn over but not fire. I tried a second time and heard some horrible noises and stopped. Had the car towed home and here we are.
Thread Starter
Safety Car
Joined: Mar 1999
Posts: 3,612
Likes: 182
From: Toronto, Canada
Race Director
Joined: May 2005
Posts: 15,960
Likes: 21
From: West Norriton PA
St. Jude Donor '08
Melting Slicks
Joined: Feb 2006
Posts: 2,184
Likes: 2
8000 miles! Completely stock LS6 motor and no bouncing off the rev limiter. I was 3rd gear at about 4500 rpms and I went wot and at about 5300-5500 rpms the engine went boom! Car shut off and I coasted to the side of the road. I tried to start it and would turn over but not fire. I tried a second time and heard some horrible noises and stopped. Had the car towed home and here we are.
5000+ rpms seems low for valve float on a stock motor.
Thread Starter
Safety Car
Joined: Mar 1999
Posts: 3,612
Likes: 182
From: Toronto, Canada
I'm no expert but maybe one the sponsors can jump in with some info for you. When I build up the motor I will definetely go with a double roller chain for sure.
Race Director
Joined: May 2005
Posts: 15,960
Likes: 21
From: West Norriton PA
St. Jude Donor '08
I used a Katech Chain in my brothers build.
Safety Car
Joined: Apr 2000
Posts: 4,326
Likes: 140
From: Weatherford, TX
How much boost, and were you running meth? 
Safety Car
Joined: Apr 2003
Posts: 4,251
Likes: 7
From: Woodbridge Ontario