New longblock wiped cam

[gophman]

They have all the images now, we'll see how they respond.

[gophman]

[gophman]

[SC/397]

Wow. To say that sucks is an understatement.

[acct21]

Well I've wracked my brain, and I can't come up with a scenario where they can pin this on improper break-in.

Is it possible to fit an oversize piston in a standard bore? Wonder if that liner is/was standard size, but the piston is over.

[440sixpack]

Since normal wall clearance is only a few thousandths, a bit more on forged pistons, it is not possible to fit an oversized piston in a bore size smaller than intended. but that doesn't mean it was bored the right size.

It looks like an oiling issue, which is hard to imagine given how the skirt gets oil. more likely a clearance problem. do any other pistons show signs of this? have you measured the bore on the failed piston and compared to a good one? if you know what pistons they used look up the clearance spec and compare it to your bore size.


I had a very similar problem on a fresh 390 in a '68 AMX I bought years ago. they bored it for cast pistons and put forged pistons in it. needless to say it didn't work at all, correct wall clearance is essential .

One thing is pretty clear, there was an issue here that had nothing to do with break in. if they won't make it right you got hosed.

[SJTD]

Interesting that the skirt is that bad but the rest of the piston and the rings are ok.

Are you equipped to measure the bore?

[TexasJ10]

Interesting that the skirt is that bad but the rest of the piston and the rings are ok.

Are you equipped to measure the bore?

Good point. Maybe it's the piston that is out of specs.

[440sixpack]

The skirt is usually what scuffs, the reason you can buy coated skirts. in this case I doubt it would have made the difference, but I always use them if I have a choice.

Scuffing on the top is usually from heat .

[SJTD]

Yeahbut then material gets deposited on the bore and the rings and the rest of the piston get mangled.

What's the bore look like?

[gophman]

Sorry for the late reply.... unfortunately I don't have any bore measuring equipment (I could aquire), the other bores/pistons look fine (aluminum) has damaged the bearing babbit but the journals are unmarked.

[440sixpack]

If you're going to find out what happened you'll need to measure the bore and a good piston. it would be best if you knew the clearance specs for the exact pistons you have if possible.

For a quick but not precise check see if you can get a .002 feeler gauge between the skirt of a good piston and the bore that scuffed. also check a good piston and bore for comparison. if it's less than a .002 feeler on a cast piston you might have found the problem, forged pistons will require more clearance.

It sounds like the rest of your engine may be fine with new bearings and a gasket set. if it's just this one hole is tight a new piston and some hone work might be all you need.

You shouldn't have to fix it yourself but under the circumstances I'd be looking at the options.

[gophman]

Yeah I am waiting to hear back from s&j but I am weighing up my options at the moment, the pistons are +60 so final bore so depending what I hear back my options so far are:
1 repair this motor (could potentially require a sleeve)
2 use the known good parts (crank, cam, heads etc) and transfer to the original block (depending on condition of original bore/pistons.)
3 reassemble the original motor (valve guide wear) and wait it out and possibly ending up carrying out option 2 anyway.

[440sixpack]

Until you find out if the bore is undersized you won't know if it needs a sleeve. maybe it needs opened up.

In any event you're gong to need at least one piston, maybe you can buy a matching single and maybe you can't. if you need a set you can order any size you desire if you're changing blocks.

[babywag]

I would not transfer any parts, if you're going to redo your engine, just go that route.
If they were that careless in providing a quality product, who knows what else they did/did not do?

I'd still push for a replacement, or a full refund, shipping on their dime.