Will an '88 XJ block fit a '99 XJ?

[88JeepXJ]

I posted this before in another thread but it got buried.

I got the itch to finally buy my buddies 4.7 stroker. The only thing is that he built it from my old '88. Do you know if my '99 head and accessories will fit on an '88 block? This stroker has a worked over HO head but I'm pretty sure I have to keep my head for emissions.

As a side note, what is a used (~40k miles) stroker worth?

 

[88JeepXJ]

Nothing? Really?

Has anyone looked at a pre '91 block and a 97+ block to see if it is the same?

 

[Brown Dog]

87-01 XJ 4.0L, 87-90 YJ 4.2L, 91-99 YJ 4.0L block bolt patterns are identical. All but one of the holes is 3/8" course.

The following from Production Engine Reman Assoc's website describes block differences: http://www.pera.org/articles/eb40319.htm

 

[88JeepXJ]

So it sounds like yes, maybe it is possible but the '88 block is greatly inferior to the 96+ design.

All I want is an XJ that produces 300hp and get 25 mpg! OK 275hp and 20 mpg would be enough.

 

[Johnnie Walker]

A GM LSx/LQ truck motor would get you more where you need to be... More poines and mileage.

 

[bigdaddyjlove]

I have a '89 block now earning its living as a 4.6 in my daughter's 98 TJ.

Short answer, yes it works fine. You may want to plug the hole for the knock sensor with a pipe plug.

IIRC everything else is identical

 

[gradon]

Keep the stroker the way it is if it's an 88 block with an HO head(7120 I suppose) on it. Your 0630 head differs in that it doesn't have an open coolant port on the driver's side back of the head(my 1/96 0630 does have the sensor still, but they removed it when they went to the ccd setup in 97), so that sensor can stay in but unplugged in your 99. Ditto on leaving the knock sensor in the block, but unplugged.