Join Date: Feb 2003
Location: Warner Robins, GA
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4.0 head overlap on 4.2 block
I'm currently installing a HO 4.0 head (#7120) on an '86 4.2 block (casting# 3227444). Two issues have come up that hopefully, some of the prior head swappers on the board here, can set my mind at ease.
1. Like the subject line implies, I'm concerned about head overlap on the 4.2 block. Other posters on the board have talked about overlap, but never gave specifics. When doing a test fit with my head on the block, I installed two head bolts on each end to make sure it's centered. I have varying degrees of overlap. And when I say overlap, I mean the triangular ports are literally exposed beyond the edge of the block, worst case 3/16" to best case flush with the side of the block. Many posters had success with epoxy, so I had planned to use dissolveable peanuts and seal the 12 ports with marine grade JB Weld. But now wonder if that's a good idea with the amount of overlap I have. Anyone else with the head swap see overlap like this and still use epoxy? Would it still be wise to go with JB Weld, or should I use freeze plugs, pipe plugs, or have them welded shut?
2. I read an '86 4.2 block, casting# 3227444, is supposed to have 7/16" head bolts. But mine has 1/2"X13TPI, verified with my tap & die set. All evidence points to the fact that the 4.2 head hasn't been off since put on at the factory. So since I have 1/2" head bolts, should I use the higher 4.0 torque settings? Anyone else with an '86 CJ-7 with factory 1/2" head bolts? Is it possible since my Jeep was a late model '86 (it has a Dana 44 rearend) a 4.0L block was used? But that wouldn't make sense because of my overlap issue. [img]images/graemlins/confused.gif[/img] Any thoughts?
LargeAl, '86 CJ-7
"You know we're sitting on four million pounds of fuel, one nuclear weapon and a thing that has 270,000 moving parts built by the lowest bidder. Makes you feel good, doesn't it?"