Head Rebuild and cam

Rebuilding a 92 head to go on my current 01 cherokee to replace my 0331 before it cracks (if it ever does or if it already has). And ive got a few questions for you guys.

The work will be done at a local machine shop (still need to consult them either fischer in edison, or Headgames motor works)

I want to stay with stock intake valve size, but i would like to go for an oversized exhaust valve. What would you guys recommend? (anything else as far as head work would also be cool)

Since the 92 lacks bosses for the coil packs does anyone make a bracket to hold up the coil rail on the 01?

Since the head will be off I would like to cam this thing, anybody have any recommendation as to what would be computer and physically compatible?

Thanks guys.

you take two small piece of flat stock bent and drilled to mount the coil to two of the valve cover studs

I would stay with stock exhaust valves due to shrouding. If you must larger valves look at the Magnum valves. SI valves have stainless valves for them. I would have them back cut to improve flow along with the 3 angle valve job.

And the cam, what do you want to improve with it?

You're freakiin me out. What's with these 4.0's, are they bullet proof? I've always been under the impression that it is not a good idea to jerk the head, and replace it without re-ringing the pistons, a light honing to the cylinders, and while there replacing all crank/rod bearings, etc., etc., etc. Old school has it that a tight head is out of balance with a loose lower end.., as far as pressures go.., and thus heavier wash down, (unspent fuel/carbon), will dump down into your oil prematurely wearing out the lower bearings faster, etc. It's really easy to do a more complete task while the head is off. I could be all wet as per the 4.0, but it's just my two cents.

Your bottom end would have to be really worn out for that to happen. Simply rebuilding the head won't increase compression that much.

Besides, if the head was as loose as to actually balance out a very loose bottom end the valves wouldn't be sealing very well.

That whole tight head/loose end breaking is a myth unless it is extremely worn. At which point it would need a full rebuild anyhow.

I have never heard any one say they killed the bottom end with a fresh head.

Thats so good to know.., about placing a restored head on an in-service engine. Just a myth, 'eh? Guess I'm a perfectionist when it comes down to tearing into an engine. Some might use another term, lol, but while I'm there... ...AND I might just as well use brand spanking new head bolts while I'm at it too.

I wonder about the compression increase versus the decrease in the mix and match old engine new head scenario you paint. You may have never heard any one say it, but I will... One fellow years ago began with cylinder pressures throughout; at minimum, and maximum allowed, and ended up developing a crack at one of the crank's counter weights, (i.e., a crystallized fracture). So many years ago.., lol.., I can't remember all the details.., like wrist pin hammering, and rod cap failures associated. Probably due to the fracture. AND HEY.., could be the crank was prone to fail regardless of the head job.

Of course I am missing something in suggesting a more complete job since I do not recall the mileage of the vehicle in question, or the compression values, plasti-gauge determinations, etc. However, it is a matter of routine for me to make those evaluations anyways. Also I do not recall reading anything about the valve condition as per leak down, and LOL. Hey, there's no problem with me if one 'feels' the situation does not require a complete checkup! Surf's Up! (some wax their boards.., some don't).

Some people overthink the process.

Guys run 4.0's upward of 12:1 on the stock crank and have them survive fine.. I'm sure going from the stock 8.8:1 to 8.82:1 with a head job isn't going to be an issue.

Myself, I have swapped six 4.0 heads without looking at the bottom end. They are all still in service, and working fine. As long as there is decent oil pressure and the cylinder walls look good when you pull the head, there shouldn't be need for concern.

thehighlander said:

Rebuilding a 92 head to go on my current 01 cherokee to replace my 0331 before it cracks (if it ever does or if it already has). And ive got a few questions for you guys.

The work will be done at a local machine shop (still need to consult them either fischer in edison, or Headgames motor works)

I want to stay with stock intake valve size, but i would like to go for an oversized exhaust valve. What would you guys recommend? (anything else as far as head work would also be cool)

Since the 92 lacks bosses for the coil packs does anyone make a bracket to hold up the coil rail on the 01?

Since the head will be off I would like to cam this thing, anybody have any recommendation as to what would be computer and physically compatible?

Thanks guys.

Click to expand...

I'm running a 93 head on my '00.
As stated the brackets are super simple to fab with some flat bar or hammered flat corner straps.
Placing the head is easier if you lip the top off a couple head bolts to use as temp dowels as the earlier head lacks this feature.
The earlier head has huge exhaust ports compared to the later 0331 head.
Plug the rear temp sender port (1/8"NPT).
The exhaust will be your largest peroblem, you'll need to make an adapter to reuse your stock exhaust, being an '01 I don't think using the earlier manifold is an option like it was on my Canadian '00 with only one upstream and one down stream O2 sensor. If it is, I can add some tips for that