Will a 1989 4.2 head fit on a 1986 engine

[OldJoe28]

I have a 1989 YJ, 4.2, 209,000 n change on motor.
I found a nice rebuild able 1986 4.2.
Vin number on the '86 block says it was built April 24, 1986.
This '86 motor has the PLASTIC valve cover, BUT, no center bolts on the rockers to hold it down, but the other hold down bolts are for a plastic cover.
My '89 motor has a " fresh" low mileage cylinder head PO installed. With a Almn valve cover.
I see all the head and intake/ exhaust gaskets for both engines are the same.
Head bolts are not,( '86 has 1/2-13 by 3"), ('89 head bolts are 7/16").
I've read,( on line), some say yes, others, no way??????
Can the '89 head fit on this '86 block with the '86 head bolts??

Here's a bit more info.
For sheets n giggles, I looked on Auto Zone web site for remain heads.
Both heads have same SKU numbers?

I'm THINKIN that if I used the '86 head bolts, it should?? work???

Joe

 

[deadpool1]

im not sure, and 4.2 are rare now.
the parts book is free to read here, the parts PDF for this car is here.
that engine is not from a wrangler. 86?
I would not ask the Zone for shoe laces, but good lock there. (most there were not even out of school then or born)
the best guide is the casted head codes. on the head not just the stamped MFG year codes.
87 to 90 head show only
quote see same.

8350 2372 1 1987 Use with plastic cylinder head cover #715
8350 3322 1 1987-90 Use with aluminum cylinder head cover #661


the engine was made from 1952 to 2006
what your came out of ,not sure me.
jeep 1964 to 2006,
the jeep book shows 1 head and works on both valve covers. 1987-90
you see year 1987 Chrysler owns all this. and offered 2 valve covers per above parts list.
jeep wiki 4.2l shows
This iron block 258 cubic inch I-6 cyl was introduced in 1971 and stayed in the jeep family until 1990.
almost a 40 year run, so sure head bolts vary that long.
used on jeeps .4.2L

Gladiator/J-Series Trucks pickups and the Wagoneer were the first to use this engine.
In 1972 the CJ's (including the CJ-5) were powered with this reliable mill. And finally, In 1987 the YJ Wrangler. tp 1990.
that engines out of CJ.?
or just he block?
lots of 258 blocks. made. so some are 1/2" you learned
what is there I dont' know
but 40 year old blocks are hard to find parts for.
dorman shows none that old


ok google finds this, history on bolts. 258 in 3 seconds and is bingo on casting codes.

mixing engine parts in 40 year range, is problematic.
good luck sorting it all out.

jeep / amc inline six 232 / 258 / 4.2 headbolts and fasteners

jeep / amc inline six 232 / 258 / 4.2 headbolts and fasteners

headbolts.com