Cobra4B

iTrader: (9)

2001 LS6 - Stock
123,xxx miles - Last 3000+ all track use
Made 364 rwhp this February during dyno verification
Had a couple lifters go last race weekend, no other issues with it

Roller tips both destroyed. Lifters weren't turned in the bore, tray was fine. Can the rollers just fail over time?

#7 Exhaust - Roller completely destroyed, pin ejected, cam lobe beat up. I don't have any pics of it out of the engine as I dropped it trying to get it out the bottom.



#7 Intake - Roller worn... probably not far from ending up like the exhaust lifter. Cam lobe wasn't beat up yet.



Camshaft


Is this a symptom of something else or just normal failure? I always though the lifter failed internally and then the removal of preload allowed it to break the tray and turn in the bore? As mentioned above neither of these were turned in the bore, it seems the tips failed first. All the other lifters were perfectly fine.

Thanks,

Brian

Glenno108

Wow that's identical to what we did in a 6L nothing but track use 508rwhp we put it down to a faulty batch of conp cam lifters, 3 sets died for us shifted to Howard's and a Howard's cam made better power and haven't had a drama yet

SS10Tech

Some serious carnage.

It is better to have too much spring pressure instead of too little which can cause this problem. Of course you want to get by with as little as possible but spring pressure is not the variable that should change - valvetrain weight is where you play this game.

Any idea on the spring pressures O/C vs registered spring pressures O/C now?

Depending on the lifter brand some of them are extremely sensitive to debree in the oil. Did you have the lifter bores chased and honed with proper clearance when the motor was built? Lifter bores can vary in production blocks by as much as .0005 which can cause problems - uneven pattern wear, improper clearance, etc.

vettenuts

iTrader: (4)

I agree, I would start with the valve springs and work from there. They are known to lose stiffness with mileage (cycles) and the stock springs have been seen to lose control at much lower mileage than on your car currently. If they lose control then the lifter will start hammering the cam. I would also check the rockers over carefully for issues.

Cobra4B

iTrader: (9)

1. The engine was OEM stock - No build

2. I put fresh '02-'04 spec springs in it mid 2010 when I built the car for the track. Car is a 2001 so these are stiffer than the '01 springs.

vettenuts

iTrader: (4)

I would still check them. High RPM and heat are tough on springs and you may find the replacement cycle is shorter due to the way the motor is run.

Cobra4B

iTrader: (9)

I have new springs already. Was going to put another set if fresh springs in along with another new timing chain and new lifters this winter. Car decided to accelerate that timetable.

dregg100

iTrader: (3)

a friend of mine had this happen to a much lower mileage ls2. We thought a contributing factor may have been low zinc oil. what oil were you running?

Cobra4B

iTrader: (9)

Amsoil XL 10w40. Just their "cheap" synthetic, but it still has a bunch of ZDDP etc.