dimetweaker

iTrader: (1)

I bought a few of these engines, both having the same issues. The VVT had a failure and we got some piston and valve contact. The first I rebuilt with forged rods and pistons, this one I want to run with stock rods and pistons, hot cam and will be replacing the intake valves with new LS3 valves. The engine builder pointed out something I didn't notice before; the valve reliefs don't actually line up with the valves. What the hell am I missing here? someone learn me. You can see where the valve made contact with the piston and its making my brain hurt

There shouldn't be PTV clearance issues with a hot cam and these pistons, so the plan is to just cam it and bolt it back together, unless there is a bigger problem here.

jerrytx

Not sure why you are having valve contact opposite the relief. I can tell you after losing engines (1 LS2 and 2 LS3 stock short blocks) due to weak springs, mis shift and broken rod bolts, that the valves break off and then the piston shatters. None of your shortblocks had a valve snap off but still the piston is likely compromised and may come apart. When that happens, the rod slaps a hole through the block and if you have longtubes the oil will cause a fire. I've had 3 fires so far. I will never run an LS in anger with stock pistons or rod bolts again. I'd recommend at a minimum you do forged pistons and ARP rod bolts as part of your rebuild.

RyanS13

iTrader: (10)

n/m it must be something with vvt

redtan

iTrader: (5)

They are setup for the exhaust valves only, which is the valve that deals more with PTV since it's the one that's open when the piston is coming up. The intake valve is only open really when the piston is all the way down in the bore, so no issues there.

Now if there's an issue and the head drops the valve more than it should, then either valve will come into contact with the piston. I'm assuming this was the case here and the intake valve was not being suspended up into the cylinder properly and hit the piston.