Alright guys here is what ive got going on in my head. Ive got an 84 Cj7 with the 4.2 liter straight six. Im wanting to rebuild the motor, bore it out, upgrade carburator and throw in a cam. Not sure what to bore it out to or what kind cam or carburator to get. I still want to be able to drive it on the road fine but tair up the trails. Ive got 3.5 inches of lift and it sittin on 35'' cooper stts. Any suggestions? Not too experienced on motors so need any and all kinds of advice. Thanks!!
Why not just pull the 4.2 out and go with a SBC. For not much more than you would spend doing a good rebuild and getting it bored and out and remachined you could put a SBC in it and get more power. Just a thought..
04-04-2013 01:23 PM
I rebuilt my I6 and a 22re out of a Toyota What did you need help with?
Just an fyi this could cost more than you think. We bored over the 22re .040 (to it's max) and with the new parts i.e. pistons, Piston rings, rebuild kit, gasket set, cost to have the machine shop do the work, ect... It came out to roughly the same price as a crate engine.
If the engine is in working condition than there is no need to bore over stock specs. One of the only reason people over bore is to gain horse power or just to resurface the internals of the motor (to make for a brand new engine). If the engine runs fine then suggest doing a compresion test and if the all 6 pistons are within 10 psi (I prefer 5) of each other that means your all pistons are wearing at the same rate, that's a good thing.
My I6 I did NOT pull the head, because when you do it is HIGHLY recommended that you bring it to a machine shop to check for warp or wear on the surfaces. This means if there is warp then the pieces need to be machine which can cost a pretty penny. So my advice is pull the heads at you own risk.
So I didn't pull my head when I rebuilt mine, I just placed all the gasket (except the head) cleaned all the parts and painted with high temp paint.