Help - Bent intake valves
Thread Starter
Staging Lane
Joined: Oct 2008
Posts: 76
Likes: 0
Help - Bent intake valves The story is a bought this LS6 from a friend of a friend. It was a runner and had been pulled from his car for another project that her did not get around to. Seemed like a good fit for my application
I picked it up missing some covers and the rockers sensors and other Misc stuff.
Specs are Ls6 block 243 head with some work. Cam is a Flowtec 228/232 .600/.600 111 LSA. has trick flow 7.40 pushrods and it came with a BBK intake
I put everything back together using some "stock rockers" that I bought which at this point was a big mistake because the first time I fired it I bent almost all the intake valves. Im new to this so it is a big *** learning mistake but to late to do anything about it. I can only conclude that the rockers are the wrong ratio fro this application and the intake valves opend to far and kissed the pistons
Here is my question given the info I have how can I figure out what rockers I should have?
The timing has been checked and given that that cam has a 4 degree advance I had it set to negative 2 on the crank so looking at 2 degree advance which should not have caused a issue.
Please help im not sure where to go from here
cam is 228/232 .600/.600 111 LSA
push rods 7.40
I picked it up missing some covers and the rockers sensors and other Misc stuff.
Specs are Ls6 block 243 head with some work. Cam is a Flowtec 228/232 .600/.600 111 LSA. has trick flow 7.40 pushrods and it came with a BBK intake
I put everything back together using some "stock rockers" that I bought which at this point was a big mistake because the first time I fired it I bent almost all the intake valves. Im new to this so it is a big *** learning mistake but to late to do anything about it. I can only conclude that the rockers are the wrong ratio fro this application and the intake valves opend to far and kissed the pistons
Here is my question given the info I have how can I figure out what rockers I should have?
The timing has been checked and given that that cam has a 4 degree advance I had it set to negative 2 on the crank so looking at 2 degree advance which should not have caused a issue.
Please help im not sure where to go from here
cam is 228/232 .600/.600 111 LSA
push rods 7.40
The wrong rocker ratio would not do this. I bet the timing set is not installed right somehow. Your valve events are way off if you bent valves when you crank the motor. Did you leave it at idle and it bent the valves? Are you 100% sure the valves were not destroyed when you bought the motor?
Thread Starter
Staging Lane
Joined: Oct 2008
Posts: 76
Likes: 0
I can not be 100% sure that the valves were OK when I got the motor. The motor came to me though a very trusted friend from another very trusted friend of his I have no reason to think that the valves were bent when I got the motor.
I was able to start the motor and it ran for less than a min before it shut down and would not fire.
Timing has been checked unless I am missing something. I am new to this but I have some experienced friends looking over my shoulder.
I was able to start the motor and it ran for less than a min before it shut down and would not fire.
Timing has been checked unless I am missing something. I am new to this but I have some experienced friends looking over my shoulder.
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
You basicaly installed the cam wrong (timing chain). And why in the world would you want to advance that cam more than it allready is.
Just get a LS2 chain and install it dot-to-dot (since you are a newb at this so no way to mess it up) and take the heads for valve replacing and guide check.
Basically you messed it up big time, your "experienced" friends do not know any better.
Look at http://www.LS1howto.com for install guidance.
Just get a LS2 chain and install it dot-to-dot (since you are a newb at this so no way to mess it up) and take the heads for valve replacing and guide check.
Basically you messed it up big time, your "experienced" friends do not know any better.
Look at http://www.LS1howto.com for install guidance.
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You are going to have to pull the heads and inspect the pistons for damage anyway. Pull the heads and take them to a reputable shop familiar with the lsx heads and do what Predator-Z said also; get an LS2 timing set and install it dot to dot. LS1 Tech Stories
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Pred. Z and 1CAMWNDR have it right on the head. Me and a buddy of mine did this exact same thing when the F14 cam first came out using a 9 way adjustable timing set, lol.
Now that the heads are off, its time to install the cam straight up and check piston to valve clearance.
Good luck man.
Now that the heads are off, its time to install the cam straight up and check piston to valve clearance.
Good luck man.
Joined: Nov 2001
Posts: 3,043
Likes: 0
From: Texas and Qatar
This happens a LOT, I've seen more people use the keyway to align the chain than anything, don't ever move the keyway slot without verifying that the #1 piston is at TDC when realigning the chain, and then follow up with a degree wheel to confirm, and then a PtoV measurement as a double confirmation. 
BTW I for S+G's measured how far the piston had traveled down the bore at peak intake lift, it was about 2.xxx inches down from TDC when the valve was completely open. Peak lift is nowhere near the piston, so interference is highly unlikely. PtoV issues happen always near overlap in the +/- 10* areas from TDC, intake is ATDC, exhaust BTDC, I usually check in 5 degree increments (5-10-15), that is usually sufficient to get a good feel of what PtoV is.
FWIW, yes, I speak in acronyms in RL.
BTW I for S+G's measured how far the piston had traveled down the bore at peak intake lift, it was about 2.xxx inches down from TDC when the valve was completely open. Peak lift is nowhere near the piston, so interference is highly unlikely. PtoV issues happen always near overlap in the +/- 10* areas from TDC, intake is ATDC, exhaust BTDC, I usually check in 5 degree increments (5-10-15), that is usually sufficient to get a good feel of what PtoV is.
FWIW, yes, I speak in acronyms in RL.
