head and timing question important

[jeremytx]

I recently bought a 95 grand am 2.3 which jumped 6 teeth at the crankshaft! Needless to say I bent all the valves and scarred the pistons. I need to know how thick the heads on those pistons are because one scar in particular is 3/8 inch long and close to 1/16 deep. There are no cracks just a dent (tested with dye and developer). If its over an 1/8 thick near the top of piston dish I'm gonna run it. Also what causes the chain to jump 6 teeth. Need a list of possibilities so I can eliminate all of them. I think the guy I recently paid to change my housing left to much slack on the crank/intake side of the chain when he released the tensioner HOWEVER I don't know for sure so lead me in all the cautious directions. Any insight will be severely appreciated hoping to have it running by the 1st.:)

[rixGAphx]

I don't know anything about the innards of a 2.3.

But a slack timing chain, for whatever reason, is generally the cause of a jumped chain.

Regardless of the piston crown thickness, the 'dent' has created a 'shear point' in the metal surface.
Just like a finger pressed firmly into a plastic bread wrapper creates a permanent weakness from which a tear will eventually, the explosive force of combustion will concentrate a the 'dent'.
You may make it 10 miles, 10k miles, or 100k miles, but that dent is where the failure will occur.
If you want to try to run it, take a very fine file and some wet-or-dry sandpaper. Remove sharp edges from the dent, since these 'stress risers' further concentrate the explosive force.

You have another issue to consider:
Anytime an upward-moving piston smacks a valve, you must consider that the connecting rod may have been bent. It's nice when the valve stems are 'sacrificial', but don't count on it.
If you keep these pistons, do a compression check after re-assembly but before firing the engine.
A bent rod will give a way-low compression reading on that cylinder.

-Rick