Hypereutectic pistons and failures related..
I've been running KB 243's in my .030 340 for yrs.
I had the same no.5 piston weld itself to the cylinder twice.
the cause was cap rotor phasing in my poorly made mopar distributor.
I was frukin pissed to find this out on the second build.
I started .020 , scuff'd, then went .030, scuff'd, sleeved the no.5 hole & bought 1 new piston ground it to the weight of the rest BTW this is when I found they started making them in mexico cause the new piston weighed 8 grams more than the usa made.
SO right before fire up of the .030 set I checked into some theorys and found the dizzy was crap, so I bought an MSD pro billet and fixed 7200rpm all day no issues.
Next the 410.....
KB356 which I told the machinist to hone for 3 1/2-4 thou skirt clearance, he said huh??
I told him I punish my stuff which is why I run mopar to begin with, he says 'uhhh ok' built into the piston right..
Being tuned in as I am to my motors perfomance I decided to do a leak down on it and found 22% on all cylinders.....
so I get into the motor and pop some valves out[due to hearing air leak out the pipes during the test] and find all the out of the package ferrea valves were out of round...owner of the shop says I ran it too lean, BUT the mix was not that lean..I mean stainless distortion point is like 2200* and the pistons melt at over 1200* so...nope to being too lean, it was a valve manufacture issue.
Well...then I get to the drivers side and find 3,5,7 all had the beginings of scuff but didn't smear or ruin the skirts and barely scrathed the upper exhaust side of the cylinder which is odd being I'm running the same oil I have in every other engine of mine for yrs now, the same oil petty driving experience runs in all their cup cars...
Even funnier is when I dropped the no.1 piston rod on my foot and then onto the shop floor...I dead blowed the skirt back into shape and installed it.....well guess what?
The no.1 piston is the only piston not to scuff on that bank....
I've had machine shop failures before, it's hard to find a good one and that makes a lot of people resort to the highest dollar shops they can find since it makes them feel like the are deffinitely getting the best.
But really it's about them knowing what you want and doing it.
Unfortunately even though I know this machinist pretty well, he's trying to find every excuse under the sun to say it was my fault, which I would except if the reasons made any sense...
I'll be sticking a bore gauge in it and see where it really is, then a hone, new rings, re grind on the exhaust valves and back together it go's
ran good for being that fruk'd up...
anyways I had a feeling I would hear good things mostly about these hypers
it's when you use them out of app that they show weakness.
this 410 motor spins 6500rpm regularly.
I've been running KB 243's in my .030 340 for yrs.
I had the same no.5 piston weld itself to the cylinder twice.
the cause was cap rotor phasing in my poorly made mopar distributor.
I was frukin pissed to find this out on the second build.
I started .020 , scuff'd, then went .030, scuff'd, sleeved the no.5 hole & bought 1 new piston ground it to the weight of the rest BTW this is when I found they started making them in mexico cause the new piston weighed 8 grams more than the usa made.
SO right before fire up of the .030 set I checked into some theorys and found the dizzy was crap, so I bought an MSD pro billet and fixed 7200rpm all day no issues.
Next the 410.....
KB356 which I told the machinist to hone for 3 1/2-4 thou skirt clearance, he said huh??
I told him I punish my stuff which is why I run mopar to begin with, he says 'uhhh ok' built into the piston right..
Being tuned in as I am to my motors perfomance I decided to do a leak down on it and found 22% on all cylinders.....
so I get into the motor and pop some valves out[due to hearing air leak out the pipes during the test] and find all the out of the package ferrea valves were out of round...owner of the shop says I ran it too lean, BUT the mix was not that lean..I mean stainless distortion point is like 2200* and the pistons melt at over 1200* so...nope to being too lean, it was a valve manufacture issue.
Well...then I get to the drivers side and find 3,5,7 all had the beginings of scuff but didn't smear or ruin the skirts and barely scrathed the upper exhaust side of the cylinder which is odd being I'm running the same oil I have in every other engine of mine for yrs now, the same oil petty driving experience runs in all their cup cars...
Even funnier is when I dropped the no.1 piston rod on my foot and then onto the shop floor...I dead blowed the skirt back into shape and installed it.....well guess what?
The no.1 piston is the only piston not to scuff on that bank....
I've had machine shop failures before, it's hard to find a good one and that makes a lot of people resort to the highest dollar shops they can find since it makes them feel like the are deffinitely getting the best.
But really it's about them knowing what you want and doing it.
Unfortunately even though I know this machinist pretty well, he's trying to find every excuse under the sun to say it was my fault, which I would except if the reasons made any sense...
I'll be sticking a bore gauge in it and see where it really is, then a hone, new rings, re grind on the exhaust valves and back together it go's
ran good for being that fruk'd up...
anyways I had a feeling I would hear good things mostly about these hypers
it's when you use them out of app that they show weakness.
this 410 motor spins 6500rpm regularly.