One valve sits lower than the rest?
One valve sits lower than the rest? Pulled my valve cover today to investigate a tapping noise that started after a cam/head swap a few weeks ago. I noticed that the exhaust valve on cylinder 7 sits a little lower than the others. As in, the tip of the valve stem doesn't protrude as far out of the head as the other valves. This means that the preload on this lifter is slightly less than the others, about 0.020-0.030" less, and might be the source of my tapping. The valve stem doesn't have any abnormal play in it. Looks normal otherwise.
They are stock 799 heads I got new, now have about 500 miles on them, milled 0.022. Cam is a 212/212 0.561/0.561 114LSA. Brian Tooley dual springs, installed correctly, not broken. LS7 lifters with about 30k miles on them, they were in the engine before the swap. I am using 7.325" pushrods which I measured to give me about 0.075" preload. Oil pressure has been fine, 45psi at idle, close to 60psi at cruise at 1700 rpm.
I also ran it without the valve cover to see how much oil was getting to the rockers, video here: https://ls1tech.com/forums/generatio...eo-inside.html
Anyone had a similar issue?
Thanks!
They are stock 799 heads I got new, now have about 500 miles on them, milled 0.022. Cam is a 212/212 0.561/0.561 114LSA. Brian Tooley dual springs, installed correctly, not broken. LS7 lifters with about 30k miles on them, they were in the engine before the swap. I am using 7.325" pushrods which I measured to give me about 0.075" preload. Oil pressure has been fine, 45psi at idle, close to 60psi at cruise at 1700 rpm.
I also ran it without the valve cover to see how much oil was getting to the rockers, video here: https://ls1tech.com/forums/generatio...eo-inside.html
Anyone had a similar issue?
Thanks!
Makes sense. I would back all your rockers off and look carefully at the valve stems then. You may have an exhaust seat working it's way out. If that's the case, you need to get it apart ASAP.
Bent valve would do this. If this wasn't there immediately after the parts swap, any over revs or missed shifts (I assume a stick) that might have let the valve tag the piston? Do you know the PTV?
That's why I'm thinking, but my rev limiter is stock, 6000rpm I think for a truck, and I've only been there a handful of times. Never missed a shift either. The pushrod wasn't bent. Didn't check PTV because my cam is such low lift, even with the milled heads.
Staging Lane
Joined: May 2012
Posts: 85
Likes: 0
From: Tri-Cities, TN
I agree that the cam is awful small to worry about PTV, but you should still check it out. Oh and lift doesn't have anything to do with PTV clearance. Duration does.
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo Learn something new everyday!
Anyway to see if the valve is bent without pulling the head? Maybe pulling the spring and spinning the valve to see if it feels strange is the best I can do.
Anyway to see if the valve is bent without pulling the head? Maybe pulling the spring and spinning the valve to see if it feels strange is the best I can do.
