I'm curious to know if there's any differences in the cylinder head castings throughout say 1987-1997?

Intake/exhaust runner cc differences? Would a 97 head flow better than an 87 head?

Also, how can you tell what year the casting is just by looking at the 4 digit number cast into the head? Does anyone have a #reference to use?

 

Head casting #'s..
87-90 : 2686
91-93 : 7119 or 7120 (the 7120 is the better of the two and was put on in late 91 through 93)
94-95 : I have no listing
96-98 : 0630
99-01 : 0331 (in 2000 they started having issues with the heads cracking)

Hope that helps ..

 

Yea, that helps a lot. Mine is the 7120 casting; sounds like I'm in luck.

Thanks so much OKC

 

www.jeepstrokers.com They have a cylinder head section in the FAQ with detailed info.

 

I'm no mechanic but I just bought a remand head for my 95 and 7120 was the # the machine shop gave me.

 

Yep I didn't say those numbers would not cross years but from the factory those are the head castings. You can still put a 7120 on a 95 and such.

Just to add I had no numbers for 94-95 in my notes but I am assuming they used the 7120 on those years as well. The main thing that changed in the years after 95 was a few things that mounted directly to the heads like the cooling sender..Also based on the factory parts catalog the 91-95 head part# was the same and it changed in 96. and 96-98 used the same part# as well. In 99 the part# changed as well.

 

the main changes for the HO heads came in 99.5+

 

Will a 91 head fit on a 96 block with no issues?

 

What main changes in 99.5?

 

2000 and up 0331 heads are a different casting than pre 2000 0331 heads. They are weak in between cylinders and commonly crack between the third and fourth cylinder... causing a small coolant leak into the oil, eventually causing vanishing coolant, and overheating problems.

 

I understand the problems with the 0331 heads. What I was wondering was what 98 JeepJeep said about 99.5 heads. He may have been confused about the XJ Cherokees of model year 1999 having 0331 heads. The 0331 head was used on the 1999 Grand Cherokees, not the model year 1999 Cherokees. There's no such thing as a "99.5" XJ Cherokee. If it has a VIN code X, it's a model year 1999, period.

If you want to keep your 1999 Jeep Cherokee, you can keep your 1999 Jeep Cherokee...period.

 

Yes

 

#2686 - 1987-1990. AMC design, called "RENIX." All twelve ports roughly in line with "kick-ups" in the intake ports for the injector spray.

#7120 - 1991-1995. ChryCo's first revision, OBD-I head (I'd nt heard of the 7119, but it's probably similar.) Considered the "best-flowing" basic head, although the jury remains OUT. Intake ports more regular in shape, and were raised slightly. This allowed for a slightly reduced angle in the port, reducing flow turbulence and increasing flow rate.

#0630 - 1996-1999 (1998 in TJ, 1999 in XJ & ZJ/WJ.) ChryCo's second revision, early OBD-II head. Exhaust ports reduced slightly, in order to retain heat in the gases to reduce catalyst light-off time.

#0331 - 1999-up (1999-up TJ, 2000-up XJ, WJ.) Final revision of the 6-242 head, may be divided into "early" (without TUPY casting mark under oil fill) and "late" (with TUPY foundry mark, starting about 2001.5 or so.) The "early" heads are the ones you hear about when you look for "0331 Club" - cracks in the upper surface of the head are common. The TUPY-marked heads had a revised casting to reduce/eliminate this. Exhaust ports reduced still farther, same reason as the #0630 head.

The #2686 manifolds may be considered "unique" - I know the intakes aren't a direct swap, and I don't believe the exhausts are, either (also, the #2686 head manifolds had EGR, others did not.

The intakes may be swapped freely among #7120, #0630, and #0331 heads - it's common to put the later "ram's horn" intake into the earlier heads. The exhausts pose a small problem due to the reduction of ports - putting a LATER head behind an EARLIER manifold will work; but putting a LATER manifold on an EARLIER head would require fabrication of an adapter/block-off plate (easy enough to do, you just need both gaskets, some mild steel about 1/8" thick, and time. Cut the plate out to match the SMALLER exhaust ports, the gasket matching the head goes between the head & the plate, the one matching the manifold on the other side.)

It should also be noted:
- The 0331 head is the only head that was manufactured for the late distributorless COP/DIS system. Putting in a 0630 or 7120 head will require fabrication of brackets to support the coil rail, these brackets may be anchored to the valve cover screws.
- The 7120 head has a port for a coolant temperature sensor at the driver's rear, threaded 1/8" NPT. The 0630 and 0331 heads do not. Installation of a 7120 head onto a later application requires blocking this port, a brass 1/8" pipe plug will do. The boss is extant on later heads, but is not machined - it may be drilled & tapped using care and hand tools (drill motor, tap set.) D&T 1/8" NPT.
- If you change the head "outside of period," use the correct spark plugs FOR THE HEAD. I believe the "reach" of the plug changed over time.
- Thermostats & housings swap freely - it is even common to put the later thermostat housing onto the RENIX head, because the 1991-up thermostat housing has a 3/8" NPT port, which is often used for aftermarket modifications.

 

Exhaust manifolds from the 2686 head are a direct swap.

The intake is also with about a 1/4" difference at the bottom of the intake port.

 

Good stuff gents