Aaron N.S.

I've been collecting parts for a headgasket repair on my 89 and my stumbling block is that all the parts stores show 96 and newer bolt kits for the 4.0. I called ARP and they say the kit for the AMC 4.2 would work with the older 4.0 engine. I want to make sure that I'm ordering the right parts. is there any difference in the head bolts with a pre HO and HO engine, do the 4.2 and 4.0 share the same bolt. I don't want to be 1/2 way through this repair and be SOL on a few bolts.

felpro kit QES71102 (96+)
ARP Stud 112-4001 (AMC 4.2)
ARP Bolt 112-3601 (AMC 4.2)

Aaron N.S.

anyone? my Cherokee is dead in the water.

5-90

The head style changed sometime around OBD-II for the 6-242 head screws, but the threads and lengths did not change.

Also, you can likely get away with using a quality socket head capscrew to replace head screws - the RENIX screws are marked with standard SAE8 markings, and SHCS are routinely H&T to SAE8 specs.

Note - "quality" != "Made in China." Don't bother with Chinese crap. American, Japanese, Taiwanese, English, German, Polish, Hungarian, Czech - all of those are good. Most of Europe makes good fasteners. Proper AN-series fasteners are good (watch for counterfeit parts.)

Yeah, I'm picky about fasteners. Generally speaking, the Chinese can't heat-treat worth a damn (apparently, they can do a good job of it if you stand over them and breathe down their necks while they're doing it - but they can't do it properly on their own.) Don't bother with a hardware store anymore - most of it is cheap crap. Look for an industrial/farm supply house, go to Fastenal, or find an MRO house.

I don't recall the screw lengths offhand, but I know they're threaded 1/2"-20. I could probably go out and find an old set to measure, or just take measurements through a head and calculate them for you...

Just went and checked - you'll need seven pieces 1/2"-20x3.25", and seven 1/2"-20x4.00". The standoffs for the fuel injection subharness may be safely eliminated (use some sheet aluminum to make a trench-shaped heat shield if you like - form it around a pipe or dowel of sufficient diameter, retain with zip-ties) and the ground on the rearmost cylinder head stud can be relocated to the rearmost fuel rail mounting screw without difficulty (a flat washer under that screw head may help - the screw is 5/16"-18, and the ring is 7/16".) The small clip for retaining the CKP harness should not be eliminated - enlarge the hole if you need to, and put it under the screw head. Use a flat washer between the clip and screw head to keep from "wiping" the sheetmetal clip out on accident. (This clip keeps the CKP wiring from getting burned through on the #6 primary tube.)

Use the same torque specs for the socket head capscrews as you would for the hex head capscrews (#11 to 100 pound-feet with PTFE paste, all others to 110 pound-feet clean, dry.)

SNIDELYWHIPLASH

Based on the following OEM numbers, the AMC 4.2 bolts should be fine for your year-

4.2 Part Qty Description

J4007307 2 BOLT, 4.5"
J4007308 7 BOLT, 3.76"
J4007310 4 BOLT, Stud - 1" Short End
J4007311 1 BOLT, Stud - 1.38" Short End

4.0 Part Qty Description

J4007307 2 BOLT, 4.5"
J4007308 7 BOLT, 3.75"
J4007310 4 BOLT, Stud
J4007311 1 BOLT, Stud

source: http://www.xjjeeps.com/com_xjjeeps/manuals/1988_-_1990_parts_catalog.pdf

More head bolts available here:
http://www.hesco.us/shop.asp?action=...385&catId=7735
http://headbolts.com/Jeep-AMC-232-24...ead-bolts.html

TheJerm

I've done 2 4.0's, one was a budget stroker and the other just needed a head. I've always just reused the bolts, 25k miles on my personal head rebuild and never had any problems. Same with other cars ive done head gaskets to. Unless your building for alot of power i just see why you need new head bolts. Ive never seen head bolts fail in street application.

5-90

Per FSM, the OEM head screws are only good for two torque cycles before failure becomes probable.

I've had three jobs where I've had to burn broken head screws out of the block - because they were being reused for a third or fourth torque cycle.

I find this interesting - despite the engine having relatively low compression and four screws per cylinder, they're still torqued to 100-110 pound-feet. The hex head capscrews are also marked with standard SAE8 markings - which shouldn't have a problem with that amount of preload in that size - but they've failed when overused, so there's got to be something different (which makes it so I don't understand why the heads are marked as SAE8 - I've used standard SAE8 fasteners before with far more preload without incident. Go figure.

I haven't figured out what's going on - but when I overhaul my engine (or just build my stroker,) it's going to have the head screws replaced with quality socket head capscrews - problem solved. (I prefer them anyhow.)