I was told a 2.8 crank out of a 85 s10 would work in one of my 3.1 blocks.they said I could use my 3.1 rods and such.does anyone know much about that?My 3.1 had a bearing go out and I think I got everything to put a 3.1 tpi together exsept the gaskets and new bearings.the cylinders in this 3.1 still have the honeing in most of them and no lip at the top.Rings even looked almost new.

 

Depends on the '85 crank. Some information says that early '85 cranks are small journal, and that later '85 cranks are large journal.

So you will need to verify the crank journal size to know for sure.

The rods in both the 2.8L and the 3.1L are the same, the pistons, however are different, partly because of the shared rod length.

 

Its just easier to get another engine, alot of guys swap out these engines, so they are not rare. I'd do a 3.4 swap.

 

Dude, with as many 3.1 engines that are out there, just get a 3.1 crank... The 3.1 pistons are dished and the wrist pins (that go in the piston and hold it to the con rod) are offset from the 2.8 pistons. I believe you'll be losing .030" in top piston height, IIRC, if you just slap in a 2.8 crank (provided you have the 2.8 HO crank and not the 2.8 weak crank...).

 

I just have these laying around and was wondering if they might go together.I havn't sean any 3.1's around here.there not very comon.the 3.4's a little easyer to find but this was just a pet thing I was thinking about to learn with.Thanks for the input.I've never put an engine together.Have done a 3.4 swap with great sucsess.

 

Um, I'm sure there's probably a TON of 3100s, seeing as how they literally came in EVERYTHING short of pickup trucks (only difference between the 2 is the notches for the 7x sensor in the center of the crank). 3.4 uses the same crank, BTW, so if you find a blown one, the crank may be salvageable.