88 Engine in a 90 YJ

In most states that have I/M or testing programs there is a rule that gasoline burning engines must be of the same year or newer as the chassis. So technically you would have a problem.

Perhaps the Wagoneer engine has been rebuilt or replaced, but I doubt it. If it has, it may have a Service Replacement Block with no VIN. In which case the engine has no model year technically as it has no number on its block, and the VIN of the block determines the legal age of the year.

However...If you were to put your 4.0 liter head on the 4.2 block and keep all the stock plumbing, et al, so it looked stone stock, and did pass emissions, probably you would get away with it because they don't look that closely as long as all the stuff is there and it passes.

But....you would be better off to get a junkyard core engine and rebuild it or buy a decent running engine from the junkyard than buy a whole vehicle just for a lower end. Or rebuild yours if you don't mind the downtime.

You must read your state laws carefully for yourself and not rely on others' advice before you do it. Especially Hughes, he'll tell you to put a Chevy in there with a piece of s*it Advance Adapter. But he won't help you when the state will not license your Heep, since obvious swaps always get the gimlet eye.

Put the two of them together. 4.2 crank & rods in a 4.0 = 4.7. The older renix efi of the '88 had a knock sensor which helps in this type of mod.

Is there a write up on this modification available?

I am kinda tossing that about Billy Ray. I have the old 88 Cherokee we are driving and a 4.2 with a new crank sitting in my garage so when this motor wears out.....

Google has a ton of pages on doing it.

That old 88 engine still passes emissions easy as is and even dropping that in like the OP was asking wouldn't be hard.

Mike

Billy Ray wrote:

Mel is getting the new engine? Hmmmmm

LOL! Well, seeing as 'she' bought the CJ7 and 'I' bought the Cherokee, you could say that....

Mike

Billy Ray wrote: