I have an automotive engine class at college and we have to rebuild an engine. I already have mine apart so I am going to use that. Here is the question, I have the tools to bore out my block and do my own heads, is it worth it to bore and stroke my 2.8? I plan on boring it .030 over. I know I have to get new pistons and rings when I bore it. I also have to get different connecting rods when I stroke it. I already have to have my crank turned so I will also need to get oversized bearings.

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Black 1986 SE V6
Automatic - 5-speed soon!
17" Motegi MR7 Wheels
P235/45/ZR17
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Sounds like you're halfway there already.

Turning the 2.8's crank will not stroke the engine, nor (I'm not an expert here, but) will lengthening the connecting rods. If I'm not mistaken, changing the crank is what's required. The 3.1/3.4 crank will fit, in fact, it's how GM stroked the 2.8 to 3.1L.

.030 pistons should not be too hard to come by. Check Silv-o-lite. Summit should be able to source them for you.

Also, if your block is pre-1988, you may want to check out "How to Rebuild Your GM 60° V6" which will show you how to improve crank oiling.

Yep...exactly what patrick said! And the oil holes need to be champhered to allow for better oiling, which the 2.8 needs desperately on the bottom end. Good luck...sounds like a fun project...and it should run great too!

To stroke the 2.8 to 3.1, all you need are the crankshaft and pistons from a first-generation 3.1 liter engine (not the 3100). Oh, and of course the piston rings for a 3.1 also You can re-use the 2.8 rods.

[This message has been edited by Blacktree (edited 01-18-2002).]

Yes it is worth it. Boring .030 over is perfect and .010 under on a used 3.1 crank no problem. You will notice more low end if done corectly. Use a Compucam 2030 cam if you have the funds.

A general question, and since it relates to any rebuild, it's fine here:

What about decking the block? Taking some off the top would increase compression, and therefore horsepower. Correct?

Decking the block should not be used to increase CR , it's used to square up the deck to the bore centerline . Also be wary of milling heads just to raise CR. The intake manifold is hard enough to seal , if you mill or deck too much , your manifold will need to be modified to seal corectly. To raise CR pick out the correct set of new pistons , and don't forget to check valve interference with the piston at TDC.

Don't use the 2030 cam get the 260...
unless you have an auto and don't shift past 4500

Thanks for the info guys. I guess I will be looking for a 3.1 crank. I was gonna have my crank turned cause the journals were kinda grooved. That was the only reason.

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Black 1986 SE V6
Automatic - 5-speed soon!
17" Motegi MR7 Wheels
P235/45/ZR17
BF Goodrich g-Force KDWS
AIM ScreenName: Black86se