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Dang. Time to formulate a new plot. In regards to the race techs, i have heard good things about them, but havent looked at pricing or anything like that.
Verify that they actually are JE pistons, there should be a part number on the underside. I would pull all of the pistons and verify that the others are alright. Sometimes they break below the top land where you can't see like between the top/2nd and 2nd/oil rings. If there is other damage then the tune was crap.
If everything else is alright and the pistons are in fact JE's (2618 alloy) and not SRP's, order a replacement. Make sure the weight is the same (no design changes), rehone the cylinder, and swap in so you don't have to rebalance the crank. Just because 1 piston looks like this doesn't mean the others are the same. Could've been a faulty injector or some other condition that caused the engine to go lean and crack the top land to hell.
Yes, pull ALL pistons, if in fact a 2618 (broken) look for bent rods.
The block bore in the pictured cylinder is BAD, thus the need for an OS piston.
Upon inspection of the other pistons, you will see a "sand blasted" appearance in the ring land areas, if so the rest of the pistons are JUNK.
NOW sure a "guess" but be safe.
The cause is detonation, a lean engine will not create this type of piston damage.
AS for HRC, yes I agree, you have never seen a piston top in a bore.
My friend Wayne Brooks started JE Pistons, today the SAME pistons are built with the SAME equipment, in the SAME building.
Just a new name (RaceTec), I was his tenth customer.
Yes, pull ALL pistons, if in fact a 2618 (broken) look for bent rods.
The block bore in the pictured cylinder is BAD, thus the need for an OS piston.
Upon inspection of the other pistons, you will see a "sand blasted" appearance in the ring land areas, if so the rest of the pistons are JUNK.
NOW sure a "guess" but be safe.
The cause is detonation, a lean engine will not create this type of piston damage.
AS for HRC, yes I agree, you have never seen a piston top in a bore.
My friend Wayne Brooks started JE Pistons, today the SAME pistons are built with the SAME equipment, in the SAME building.
Just a new name (RaceTec), I was his tenth customer.
Lance
Pssssssssssssssssssssssssttttttt... a lean condition increases combustion temps which in turn leads to preignition. The excess heat of a lean condition could've also caused the malleable 2618 piston to swell, closing the PTB clearance and scuffing the bore. This is a low compression FI motor, equal fueling and distribution are extremely important. I wouldn't be surprised if a high flowing ball and seat PTE injector was crapping out or not as consistent as the others. If the timing was too high across the board then there would likely be similar damage in other cylinders, but the damage is limited to a single bore/piston as far as we know right now.
Like I said, tear it down and check all of the pistons/bores. Pay attention to the rod bearing of the bad piston and the rod itself. If you can get away with honing the cylinder and a replacement piston without the PTB being too loose then do it and save some money. If the motor is a 383 then it is already .030 over, boring farther can become a problem if you plan on boosting it.
Thanks everyone for the input and options. I'll post some pics of the other pistons just so you can see.
Possible where the gasket blew? Just another pistion pic
I would tear the entire engine down, have blocked checked to see WTF it takes to make it right. Carefully check crank, rods and other pistons and based on those results...make a plan to move forward
during the above process I would want to confirm the "why" this happened and deal with whatever adjustments in that area so this does not happen again for the same reason
best case scenario would be replace just the one piston, hone the affected cyl and re-ring....but I suspect that x 8 needs to happen if a hone won't clean this up .030 over bore needs to happen. If this is already a .030 over motor...get another block
AS for HRC, yes I agree, you have never seen a piston top in a bore.
Lance
???
Huh? That didn't make any sense what so ever. Care to clarify? I built my engine. I've built many. They all still run with at least 40k+ miles each on all of them. So I've seen plenty of pistons in the bore, never a gap that big. I've not built a boosted motor nor used those pistons, hence the question.
BTW, a lean condition can cause detonation........ and pre-ignition. But you go on about those bad techs.....
That gap does indeed look "yuuuuuuuge." With the marks on the cylinder walls it does look like the pistons are rocking in the bores.
Ok, I'm ignorant - I admit. So on this subject, if the piston calls for .005 clearance, is that .005 all the way around? If so, then when the piston is down against one side of the bore, wouldn't the clearance be like .008-.010 or even larger? Or is it .005 total?
Ok, I'm ignorant - I admit. So on this subject, if the piston calls for .005 clearance, is that .005 all the way around? If so, then when the piston is down against one side of the bore, wouldn't the clearance be like .008-.010 or even larger? Or is it .005 total?
I made the mistake of buying a used motor from a member on here.
Who was it?
Originally Posted by atlantadan
If so, then when the piston is down against one side of the bore, wouldn't the clearance be like .008-.010 or even larger? Or is it .005 total?
Some side loading and traces of vertical markings are normal even with the proper piston/bore clearance. The larger the stroke, the deeper the piston goes into the bore, and the more side load you may have. IMO however, that does not look normal.
02-19-2017, 08:02 AM
Piston damage? 
