Mechanical Over Rev!?!
Thread Starter
On The Tree
Joined: Dec 2001
Posts: 147
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From: New Jersey
Mechanical Over Rev!?! I currently have the spring kit installed on my stock head LS1 Trans Am. After a mechanical over rev a 2-1 instead of 2-3 shift I had a ticking and a noticeable loss in power along with popping in the exhaust on decel. The cam I am using is TSP 224/224@114 w/.581 lift. I am using Comp OE replacement lifters (5K Miles since last rebuild) The machine shop I brought the heads disassembled the heads and found no bent valves but they are concerned about seat pressure with the springs. They have inquired about install height on the springs and have suggested that some machining of the spring seats is required to ‘tame’ the pressure a little bit. Is this really necessary?
Is it possible that I have crushed some of the lifters? Also when I disassembled the engine and pulled the heads I noticed that the plastic retainers for the lifters were loose on the passenger side.
Can anyone advise what I should do here?
Is it possible that I have crushed some of the lifters? Also when I disassembled the engine and pulled the heads I noticed that the plastic retainers for the lifters were loose on the passenger side.
Can anyone advise what I should do here?
Uhh don't machine the spring seats. You probably did crush some lifters or bent some pushrods if the valves are not bent. Obviously something is wrong in there and if it isn't the valves, well that only leaves the lifters/pushrods.... for the most part. You could have damaged the cam as well, but let's hope that's not the case.
Thread Starter
On The Tree
Joined: Dec 2001
Posts: 147
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From: New Jersey
the pushrods are hardened and are straight. I removed the lifters and visually they all look fine. Also a quick visual inspection of the cam, from what I can see it looks fine as well. Thanks for the replies.
Mike
Mike
Where there any visual clues pistons collided with valves? Very easy to see with an engine that isnt brand new. You would have noticed carbon missing from the pistons and shiny aluminum in places assuming actual contact was made. If so, go over all the valves and put them in a drill press or a valve grinder and spin them...you might have one or more with a slight "kick" in it or worse.
Regarding spring pressure, how much is too much?....You haven't given us any details....150-160 on the seat is about the most you want with a hydraulic grind and somewhere around 400 lbs. of open pressure. If the combination has been running well I probably wouldnt mess with any of the installed heights.
Good luck and keep us posted as to what you find out.
If everything checks out fine (double check your pushrods for straigtness) I might advise you to replace your lifters as well if you were fairly sure you were experiencing valvetrain related noise after the over-rev.
Tony M.
Regarding spring pressure, how much is too much?....You haven't given us any details....150-160 on the seat is about the most you want with a hydraulic grind and somewhere around 400 lbs. of open pressure. If the combination has been running well I probably wouldnt mess with any of the installed heights.
Good luck and keep us posted as to what you find out.
If everything checks out fine (double check your pushrods for straigtness) I might advise you to replace your lifters as well if you were fairly sure you were experiencing valvetrain related noise after the over-rev.
Tony M.
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From: Gateway International Raceway
I am still inclined to think it might be the push rods. Mechanical over rev is the most common cause of valve float and bent push rods, I think. What ever the case you are on the right track. Let us know what you find.
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Thread Starter
On The Tree
Joined: Dec 2001
Posts: 147
Likes: 0
From: New Jersey
The pushrods all seem to be straight, but I will 2x check them. They are TSP hardened pushrods. I have ordered another set of lifters comp oe so I will put it back together like that.
According to Gunner@patriot-performance the springs are between 135-145lbs @ 1.08 and between 350 and 360lbs open.
According to Gunner@patriot-performance the springs are between 135-145lbs @ 1.08 and between 350 and 360lbs open.
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