Yeah it cranks by hand.

 

Is the timing chain unbroken or broken? Does the cam have any score places from a lotta load?

 

It's not the rod if the piston still moves. What valve springs are you using? Could have floated a valve to cause it to contact the piston with stock springs>

 

Timing chain intact, cam looks to be fine.
Running stock springs. Something had to happen to let the piston hit the valve or vice versa.

 

More lift and duration from stage 1 cam needs stiffer springs to stop them from floating. The valves float with the stock cam and springs.

 

Timing has too be the culprit. The valve stuck it's head out at the wrong time. How did you time the machine?

 

THis is a solid lift set-up.....valve float not possible. Spring bind is possible with too much cam.....which would happen too everyone with the stage 1 and stock springs.

 

Let me elaborate.....a solid lift set-up can experience valve float.....just highly unlikely in this situation.

 

I set my timing by the holes in the camshaft, the marks on the cam sprocket, the mark on the decompression mechanism, and of course TDC on the flywheel.

 

I agree garyc660r, timing had to be the issue with this failure, or one valve adjusted to tight. Anyway sorry to here about the valve drop.
I over rev'ed mine several times and never had a problem.

I have a set or stock valves if you are interested, just PM me for details.