'00xj

The cylinder head on my '00XJ was cracked and replaced with a 1996-1999 #0630 when I bought it.

How will this affect performance?

What is the upside or down side of this swap?

What's the best cylinder head that could be on this vehicle?

Engine and head were rebuilt just before I bought it by Don Wise machine shop in Oklahoma City. Only parts reused were the push rods.

'00xj

Is there anything from the #0331 head that would have been lost in the swap?

TrekkerJmm

Hi I'm not 100% positive but I believe the 99 was the best year. I'm sure someone will chime in with more info...Tj

xjbones

on a 2000 im pretty sure they are all coil on plug heads. they have holes with threads for the coil packs to bolt to the head. i think you can only use 2000-2001 heads on a 2000.

'00xj

Thanks. I know I sound green, but I'm not sure what to look for...

You're saying the COP/DIS ignition system (Coil On Plug/Distributorless Ignition system) fits on the 2000 cylinder (#0331) head but not the earlier #0630...right?

Any suggestions what I should look for to see if something's missing?

jeepkid03

Your best option might be looking for the 0331 casting number. Its on the driverside right above where the intake manifold meets the head. You might have to look pretty hard with a flashlight and brush off some dirt and grease to see it. If you have an earlier head but still have the coil pack then look for metal tabs on the head that look to be fabricated. It is possible to put an older head on a '00-'01 cherokee but tabs have to be fabricated to fit the coil pack on.

To tell if it has coil packs: Look for a distrbutor with plug wires leading to the spark plugs. If you can't find a distributor or any plug wires than you have coil packs.

How long ago was the work done? My bet was the shop probably just used a newer 0331 casting, so that they wouldnt have any issues with it fitting.

edit: the black thing on the passenger side of the engine (where the red arrow in the pic is pointing) is the coil pack

'00xj

Thank You. I read your post and went outside and looked. The casting casting number was 6330.

There were three black boxes in a row in the location you showed by the red arrow in the picture. I didn't see a distributor or any plug wires. On at least one of these there was low bolt shaft coming out of the long surface they were on (not sure what its called), secured with a nut.

The work was done in July. You mentioned a newer 0331 casting, so that they wouldn't have any issues with it fitting - is it possible they used some kind of adapter?.

I know more than before, but still much to learn, I guess.

jeepkid03

Yeah about the newer casting, i'm not sure exactly what they did... They could have gotten a new head from chrysler (a newer 0331) or gone with an aftermarket company such as Alabama cylinder head which is more likely. I have an Alabama head on my XJ. They come strengthened to prevent cracks.

'00xj

(Thinking about keeping the jeep a long time, restoring it, want it reliable +).

Wondering if the #6300 head is a good one, and whether I should get an Alabama head?

Just not sure what I gained or lost in the swap in terms of flow, power output, etc.

jeepkid03

It should be fine. Any head is better than the 0331 head, and even then not all 0331 heads crack. I know of people who have many miles on an 0331 head without issues, then some others who had theirs crack. Its a hit and miss kinda problem. Yours should be fine since its a different casting.

My engine overheated with my 0331 head and it still didnt crack. Its actually sitting in my garage right now with no cracks. I just got a really good deal on an Alabama head from someone my dad knew so I put it on as a preventative measure. If your XJ seems to be running fine the way it is then I wouldn't worry about it.

'00xj

Thanks very much for the information!

I've read tech threads about different cylinder heads but couldn't tell which heads were best.

While I normally wouldn't mess with a good running engine, I like what I saw on the Alabama head. Checked it out at Quadratec and it looks like a good option for a guy who wants to go resto-upgrade for a vehicle he wants to keep in the family for a while, or wheel the heck out of it in a pinch.

Still less than 2000 miles on the rebuild. Wondering, if I decide to get one, should I do so before I get much wear on the block?

Got a strong shake in the front end at idle, that goes away after I turn it off, and restart.

Found a broken blade on the driver's side fan. Could a fan cause that much shake? Maybe its an engine mount? w/ (190, 000 + miles on the vehicle?)

jeepkid03

My Alabama head seems good so far. I haven't even had it a month yet though. It might be a tad stronger but i'm not sure if its worth ripping into your engine if the current head is fine.

As far as the shaking... See if you can look at the engine while its shaking, it might give you a clue whats causing it. I would check the motor mounts like you said, especially after 190K miles. You said the fan blade was broken, and that would definately cause vibration. How do you think the fan broke? I've never seen that happen before.

'00xj

Sorry I was away from my computer for a couple days. I'll have the motor mounts checked, keep it parked until then. You are most likely right about not messing with the cylinder head. My wife was driving out of the driveway onto the main road when the shaking first occurred. She stopped, popped open the hood, and found one of the fan blades sitting wedged part way into a pulley.

A few random bits of information, probably too much: Can't say for sure when the fan blade broke. With the engine having been out, I do know the mechanic doing the rebuild removed the header piece, radiator, etc., front of the fenders. Not certain what exactly broke the fan, but the vehicle shows a little history. Have a couple of shallow dents ether side of the cracked and repainted plastic grill vent near the windshield, which seem to indicate the hood's been off in the past. There is a Rusty's intake, though the filter doesn't seem to match, a generic after market trailer hitch bar in back, and the rear bumper skin was slightly pushed in to one side, unless it was deformed some how by towing something too heavy for the set-up.

As I was about to buy it, the seller wanted to first fix two noisy rockers. Fixing these revealed a cracked head. I'd always heard it's best to have the same amount of wear on head and block, so paid a small portion of the rebuild cost to have it done at the same time. Basically, not sure when the fan first cracked, but there's been some work done along the way, and I'm guessing it's pulled a camper before, perhaps related to the bumper dent, the cracked head, but it's just a guess.

Most likely the fan cracked when the engine compartment was open during the rebuild, and came apart after a couple hundred miles.

SilverXJ

There was never a 6330 or 6300 head casting used on the 4.0L block. Only these:
2686 - 1987-1990 242ci
7120 - 1991-1995 242ci
0630 - 1996-2000 242ci
0331 - 1999-2006 242ci

98 JeepJeep

0331 had the smallest exhaust ports to speed the heat up process for emission reasons......
0630 and 7120 are the best flowing performance heads...with the 7120 being a little better.........leave the 0630 alone...