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Topic Review (Newest First)
05-19-2013 02:44 PM
c5wagner I had to bore it out a little bit to get rid of the scratched wall, and my engine was already at .050". Everything is fitting like it should, and I decided not to go with the 4.0l head because I don't see it being worth it. The only big change I'm going to do is the howel fuel injection kit and get rid of the POS carter. And nobody needs to worry about me screwing up my block, I'm almost done putting it back together.
05-19-2013 11:21 AM
Nubby55 If you are going to bore and buy new pistons, rings, gaskets and use a 4.0 head anyway, think about using a 4.0 block with your 4.2 Crank Shaft and Rod and build a stroker? 4.7cid
05-19-2013 11:14 AM
Nubby55 These old blocks are get harder to come by so pls don't bore it any larger than need be, there's no real HP gain in just boring a block an extra .020" or .030", then it may be able to be re-bored at a later date.
05-19-2013 08:18 AM
wittmore I live in north-eastern South Carolina - the only advice I can give you is BE CAREFUL - DON'T screw up the block!!!!! Finding replacement blocks is almost impossible - at least within 250 miles of here! Other than that it is just a motor.

One more point - my 1988 YJ 4.2 is a "flat tappet" engine and REQUIRES a zinc-based oil!!!
05-19-2013 12:31 AM
c5wagner Good to here that it isn't too bad, after pulling my engine apart though, I found one cylinder with very slight scratched wall, I'm just going to bore out to allow for slightly bigger pistons .050 to .060, I've also decided to go ahead with the 4.0l head swap.
05-18-2013 02:38 AM
Originally Posted by c5wagner View Post
I am considering a rebuild for my 4.2l i6. Has anyone done this and have any warnings or problems I could face. I have rebuilt plenty of chevy big blocks so I have the basic experience.
Im doing a full rebuild on my 4.2l right now. Ive helped rebuild everything from old flathead 6's to big block fords and this isnt any harder and easier than anymodern engine. I have a oem shop manual and also cj7 manuals come in handy as its almost identical to 82-86 models. When I have more time ill post more info.
05-17-2013 09:49 PM
Anyone rebuild the 4.2l

I am considering a rebuild for my 4.2l i6. Has anyone done this and have any warnings or problems I could face. I have rebuilt plenty of chevy big blocks so I have the basic experience.

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