KCS

iTrader: (20)

Not when the piston is intact like this one. When the piston shatters and the rod gets loose, that's usually when I've seen the sleeve crack. When the valve basically just punches a hole in the piston, it's only LS7 blocks that I've seen crack. The other aluminum blocks seem to be okay.

Just a general observation I've noticed over the years.

ayousef

other side looked perfect, now I posted the other side of the block, trying to figure out whats with the weird stuff on the edge of the piston, most evident on the pistons to the left (going by the pic)

No broken springs, and nothing that looks out looking at the heads from the top, the motor however did break two valve springs and a rocker arm EARLY in its life like before it left the shop, those were replaced, and then all of the springs were replaced again after the cam swap.

The motor has 12,000KM since the motor build, and about 6-7,000 KMs since the cam install. I would have thought things should have shown up earlier at least.

The car went to 7000rpms more than i can IMAGINE, it was tuned on the street and on the dyno and that required going through all the rpm ranges/loads etc... it felt and sounded fine for the whole time, then all of a sudden kaboom...

A3VETTE

iTrader: (2)

Ouch!

hymey

so whats the verdict? not ptv clearance due to to much preload? Run to much preload the lifter pumps up and get contact on the valve. Even if the springs have good pressure,lifter pump up and little ptv clearance f&^%S them everytime. Not that this is the cause but seen it more then once. Run good lifters and 20-40thou preload not 80. Rocker geometry may also be the cause. Sucks though, big heavy 1 piece stainless LS7 aftermarket valves work like a heavy slide hammer and break lifters and pull valves thru collets. 2 piece light valves break. A 1 piece staio with 7mm stem is the go. Unlucky.