misterp Posted July 30, 2007 Report Share Posted July 30, 2007 motor wasnt lean or ran on n2o. that hole is the valve stem that punchered the piston I would need to see the rest of the valvetrain to assess what happened; if the retainer & keepers are still in one piece then yeah you floated a valve and it kissed the piston, else you had a faulty retainer. Mr. P. Quote Link to comment Share on other sites More sharing options...
Quik Posted July 30, 2007 Author Report Share Posted July 30, 2007 I would need to see the rest of the valvetrain to assess what happened; if the retainer & keepers are still in one piece then yeah you floated a valve and it kissed the piston, else you had a faulty retainer. Mr. P. the springs are still attached to the valve stem. keepers and retainers are still intact Quote Link to comment Share on other sites More sharing options...
misterp Posted July 30, 2007 Report Share Posted July 30, 2007 (edited) the springs are still attached to the valve stem. keepers and retainers are still intact Total bummer man, you floated that valve bad enough to tear the head off the stem The good news is that it looks like the block is salvageable; get a replacement piston, rod, cylinder head, valve, springs, & re-ring kit and it'll be back in action. On my Pontiac 400 failure the head of the valve was embedded into the piston crown and the resulting expansion of the piston split the bore horizontally; if you are really lucky then the head of the valve did not contact the cylinder walls and you might be able to salvage the block with just a clean-up hone. You need to re-evaluate your spring requirements, and I would add another 0.010" to the quench height since you drive a manual (0.040" - 0.045"). That's still gotta really hurt though, sorry Quik I know the feeling. Mr. P. Edited July 30, 2007 by Mr. P. (see edit history) Quote Link to comment Share on other sites More sharing options...
Quik Posted July 30, 2007 Author Report Share Posted July 30, 2007 Total bummer man, you floated that valve bad enough to tear the head off the stem The good news is that it looks like the block is salvageable; get a replacement piston, rod, cylinder head, valve, springs, & re-ring kit and it'll be back in action. On my Pontiac 400 failure the head of the valve was embedded into the piston crown and the resulting expansion of the piston split the bore horizontally; if you are really lucky then the head of the valve did not contact the cylinder walls and you might be able to salvage the block with just a clean-up hone. You need to re-evaluate your spring requirements, and I would add another 0.010" to the quench height since you drive a manual (0.040" - 0.045"). That's still gotta really hurt though, sorry Quik I know the feeling. Mr. P. the bore looks clean. i dont think rod is damage but wont know till i tear it down. as for next time around. im seriously considering boost. and right now twins have been on my mind. the motor even the way it sits would idle with 60psi. but the funny part is others on other sites swear i didnt have enough clearance. the rest of my pistons dont have any eyebrows at all. and the fact that the truck would pull hesistate then pull again would be an indication of valve float. i experienced valve float on my old notchback 5.0 and it was what i based this experience off as well. with this happening to my truck, it allows me to spend more time cleaning up my harness along with a few other things. im going to remove all the wires that arent used anymore [rear 02s, auto crap,evap shit and etc] and possibly reroute the harness so its a cleaner engine bay for next driveline Quote Link to comment Share on other sites More sharing options...
zippy Posted July 30, 2007 Report Share Posted July 30, 2007 I would think it's just valve size, spring pressure, and rpm as you were guessing before. Those were stock valves I assume? Quote Link to comment Share on other sites More sharing options...
SS_bnoon_SS Posted August 1, 2007 Report Share Posted August 1, 2007 it lines up with the spark plug, the other side is where the valve started floating.... don't mess with me with sarcasm... running lean with maybe a little nitrous with maybe wrong gapped spark plugs.. It wasn't sarcasm. There are no signs of meltdown at all on that piston. Melted pistons turn white from being lean, not to mention the texture of the piston itself changes dramatically. N2O melted pistons change even more dramatically. Quote Link to comment Share on other sites More sharing options...
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