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-   -   4.0L head bolts (https://forums.off-road.com/jeep-short-wheelbase/77118-4-0l-head-bolts.html)

TiminMb 07-02-2001 11:06 PM

4.0L head bolts
 
Can anyone tell me how long the 4.0L head bolts are and what torque they are to be tightened to? I'm lookng for some 1/2" course thread head bolts that are 3 3/4 long on the spark plug side and 4 1/4 on the intake/exhaust side to fit an 84 4.2 head onto an 80 block (which has 1/2" head bolts). Can't use either's original bolts as they are either the wrong length (the 80 uses 1/2" but all are 4 1/4 and the 84 uses 7/16" but some are short (spark plug side)).

Does the 4.0L use short bolts on the spark plug side?

Closest match I can find are small block chrysler head bolts, some of which are 3 1/2 long.

Help!

Tim

84 CJ7, 258, HEI, M/C 2100 carb, 5 inch lift, RS9000's, 33x12.5 BFG M/T's, Lockright, full cage & belts, Xenon flares, AMC 20 1pc axles, GM dual diaphragm brake booster

Jaffer 07-03-2001 08:54 AM

Re: 4.0L head bolts
 
Recheck your thread depths in your block, will ya.
I don't recall either syle having staggered head bolt lengths... but my memory could be faulty ...
If you are putting an '84 head on an '80 block, both 4.2s, there is nothing 4.0 to speak about...
For a 4.2L block, both the Hayes and Chilton Manuals recommend 85 ft/lbs or all bolts except #11, which should be torqued at 75 ft/lbs.
The spec for a 4.0L is much higher at 110/100 ft. lbs.
Using the higher torque spec of a 4.0L on a 4.2L block can cause cylinder wall distortion on torque down ... a bad thing so don't fudge it.
The only best way to use the 110/100 spec on a 4.2L block is to have a torque plate (you can rent one from Clifford) bolted to the deck at that spec during cylinder wall boring which negates cyl wall distortion.

JAF
http://www.monsterslayer.com/jeep

TiminMb 07-04-2001 09:38 AM

Re: 4.0L head bolts
 
Found my head bolts. Went to a local jeep restorer, "The Jeep Doctor" and he let me sift thru his boxes of parts from pulled apart sixes. Seems some 4.2's did come with 1/2" head bolts that were shorter on the spark plug side. Manual says 1/2" bolts are to be torqued to 105 ft lbs. Just like a 4.0L. Put her back together last night and it's purrs like a kitten. Replaced the one noisy lifter and that eliminated the tapping noise I have been hearing for the last 3 years!

Can't believe that an 84 CJ used 3 different fasteners for the valve cover! AMC keeps me laughing!

Tim

84 CJ7, 258, HEI, M/C 2100 carb, 5 inch lift, RS9000's, 33x12.5 BFG M/T's, Lockright, full cage & belts, Xenon flares, AMC 20 1pc axles, GM dual diaphragm brake booster


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