'80 CJ7 Frankenstein 4.0

[Jackpine877]

Moving this question from another thread originally just concerning CJ7 Transmission upgrades.

Here's the deal. I finally removed the front clip and tub from my bare bones CJ7 trail rig the other day for a huge list of upgrades this winter. I then noticed a small head gasket leak on the furthest back cylinder. So, I decided to just pop off the head and take care of it now. Upon further inspection stupid me somehow hadn't noticed my head is yes from a AMC 258 i6 / 4.2l AMC 258 i6 / 4.2l , but cast into the block plain as day "4.0L-1". Followed by a proud Chrysler symbol and a casting date of 1994.

This is my first CJ build, but honestly I have no idea how I hadn't noticed it before.... Sooooo, drop on a 4.0 head/ exhaust manifold & use the AMC 258 i6 / 4.2l intake to stay carbureted is what i'm thinking? Cylinders on the 4.0 block look OK, would have done a compression test first If I had been thinking at all. Worth a full rebuild maybe?

 

[Torxhead]

Since you have the head off, check the ridge buildup at the top of the cylinders. You could ream it if it seems excessive.
Look at the valves for any sign of warpage or leaking.

 

[Jackpine877]

Thanks for the response torx. The ridges aren't that extreme from what I can tell but noticeable enough. That definitely something I'll look into doing. They could use a good cleaning up. Trying to honestly avoid a full rebuild but if it becomes necessary I'm ok with it. There looks like there could be some very slight leaking on a few of the valves. Each cylinders valves look different in terms of wear basically. Some are a bit hotter and others you can definitely tell were on the cold side.