C&N Auto

I'm not sure if this is the right place to post this but I'm in the middle of trying to get a new gen 2014 (LV3) 4.3l rebuilt. Motor had 318XXX on it and began to misfire. Low compression in cylinder 1. My machine shop guy says he needs .040 over pistons and he can't find any pistons anywhere. I checked rock auto and even called summit and they say nothing available as well. Called 2 other machine shops i deal with as well and they couldnt find anything. Does anyone know where to find some or a work around for this. I had hoped it would be just like the old 4.3l where you could use 350 pistons and I could use some 5.3l pistons but their bores are pretty significantly different sizes. Any help would be appreciated, motors been at the machine shop for 3 months.

Tremelune

Oof, aren't they the same as the V8? I thought the whole thing with these engines were that they were LTs with two cylinders chopped off...

Tremelune

Could you bore it out to fit the L86 6.2L pistons...?

Racer-X-

"Even fire" 90° V6s like the LV3, and the old even fire Vortec 4.3L (L35, LU3, etc.) have different rods and pistons than the V8 engines that share the same bore and stroke. The issue is, to get "even fire" on these engines, the crankshaft pins have to be split into two sections, offset 30° between the two banks. The result is that the rod journals on the crankshaft are significantly bigger, and the rods themselves are bigger at the crank end, and slightly thinner. Thinner rods mean different pistons as well. On the LV3, the pistons on the left bank are different from the pistons on the right bank, as well.

I've looked at the LV3 for a 2nd Gen S series I have here that needs a motor, but my engine builder says that very little is available for oversized pistons for a rebuild. The only thing I've found is 0.25mm (~0.010") over. GM also has some that are slightly over size, but less than that, around 0.10mm over standard.

If you get one of these blocks with an issue in a bore, you have to sleeve that bore for the stock pistons. That's about your only choice other than getting another block casting.

C&N Auto

I thought the same because of the old 4.3 and the LS 4.3 but I guess it's a whole different ball game with the LTs.

C&N Auto

I actually found out that silvolite makes pistons up to .040 over. I called them directly and they said they just haven't been producing them. They said production would start up again in mid-late May. So now i just sit and wait i guess.