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Discussion Starter · #1 ·
Finished \'93 4.0 head on \'85 CJ 4.2 block: A few words of wisdom.

I really don't know if it is wisdom..maybe just experience. Overall the conversion was not bad. (1) I did block the water ports on the exhaust side of the 4.0 head and used JB Weld Original. (2) Used the 4.0 head gasket. (3) needed to use the thermostat housing from the 4.0 as the housing from 4.2 resulted in the hose rubbing to close to the front of the head. (4) Used the clifford performance stats and installed 2.02 and 1.75 stainless steel values, hardened seats, and brass guides. I tried using high performance springs from the 4.2, but the pedistal that the springs sit on in the 4.0 is slightly different that the 4.2 resulting in what I thought would be a too compressed spring that already had about 175 lbs - so went with the 4.0 stock value springs. Unfortunately, I also shaved the head 60 thousandths and the shave combined with what appeared to be some variation in actual head thickness or head gasket thickness resulted in my push rods being a bit too long. I compensated for that by placing a stainless steel washer 60 thousandths thick under the rocker arm and on the pedistal. That seem to provide the correct value opening. (5) The intake from the 4.2 fit on the 4.0 very nicely with no problema. And the stock wrangler header exhaust fit in nicely. The power steering bracket required some alteration, but merely drilled a nother hole in the braket for the bottom mount and use a heavy strap metal with two drilled holes to link to the top mount for the power steering. The washers that were used on the 4.2 to hold on the intake and exhaust manifolds were to small to work on the 4.0 given the need to lift the intake manifold. On a temporary basis I used larger washers that I ground on certain sides so they would fit. So far they are holding, but will more than likely need to fabricate some thicker steel washer for that purpose or if washer off 4.0 will work to use those. With some advancement in timing and considerable retuning of the weber it is running nicely. Unfortunately, a weber just doesn't seem to have the juice and air to match the changes.

Well, just for what it's worth.

Mindbender
CJ7 258
 
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Discussion Starter · #2 ·
Re: Finished \'93 4.0 head on \'85 CJ 4.2 block: A few words of wisdom.

Wes,
Great write up...we need more like this......wish I could offer some help but it looks like your leading the pack on this one.

I wish we had a central data base where we could collect write ups such as yours so it would be more available for the rest of us.

Once again, good job.

John......southern CA
84CJ7, 3"lift, 32"BFG, 4.10's, ARB Locker, Solid Axle's, Durabak
 
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Discussion Starter · #3 ·
Re: Finished \'93 4.0 head on \'85 CJ 4.2 block: A few words of wisdom.

Great write up. If you need more information about the 4.0L Head upgrade. John Fontz has my 4.0L Head Q&A posted and Engine Upgrade on his web-page. Maybe we could talk him into adding more.

Checkout this link. http://monsterslayer.com/jeep/

Tim Weaver
89-YJ 258MPI, 4.0L Head, Borla Header, Auto

P.S. I have only two problems with my upgrade. One, I modified the power steering bracket and it broke. Two, my 17-year old son drives it all the time.
 
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