Dead 4.0

[thraxer528]

Hello everyone. I am new to the site however I believe that I have a grasp on what I need to do.

Yesterday on my way to work without warning my 2001 XJ decided to toss a connecting rod right through my oil pan. Great. So here I am. My initial plan was to grab a junkyard motor and toss it in but then decided that I would have the possibility of being right back in the same position sooner than later. So here is my plan.

Pull my engine and diagnose how bad the internal damage is. At a minimum I am planing on a new crank, rods, and pistons. (obviously bearings gaskets oil pump and such)

If the block is not totaled I will send it out to be checked out and bored the necessary size over. Once I get the block back I want to do basically the same build as the following link.
http://www.rockcrawler.com/techreports/ ... /index.asp

258 crank and rods, not sure on the camshaft yet.

My 258 donor engine is out of an early 80s CJ and the 4.0 is out of my 2001 XJ. I know that there are many differences with the 4.0 blocks but from what I have read the internals really don't change.

Please let me know if I am leading in the right direction or if I am way out there.

Thanks,
Phil

[gradon]

Have you been having any coolant issues? Any chance there is some in the oil? The 00/01 0331 heads are known for cracking(usually b/t 3 and 4 exhaust ports under the valve cover).

[Cheromaniac]

Yeah, I'd be willing to bet that the head was cracked causing a slow, chronic loss of coolant into the crankcase, contaminating the oil until it wiped out the bearings. One rod bearing probably spun and the rest is history. How many miles were there on the engine?
If the block and the camshaft are still good, you could just overbore the cylinders +0.020" and rebuild the engine with a 258 crank, 258 rods, and 677CP pistons to make a copy of my "poor man's" recipe. The existing timing set should be OK so just replace the oil pan and oil pump to complete the bottom end, and source a good used 0630 head to rebuild the top end (you can reuse your stock valve springs/retainers/locks, rocker arms, and pushrods).

[thraxer528]

Thanks for the replies guys.

The engine has 146k on it and it has been taken care of since 95k because my brother or I has owned it since then.

My initial thought was a cracked head also and it could be, however there is no coolant in the oil at all. The oil actually still looks surprisingly clean. I haven't pulled the head off yet to inspect it.

Last night I got the engine ready to pull and as I was unbolting the motor mounts I found a hole in the block. So I guess my plans have changed. I am not sure what is the best way for me to go now. I really would like to put together a 'poor mans stroker' so I guess I should begin trying to locate a block.

If my head is ok should I try to salvage it or pick up a 0630 somewhere?

Also I know where I can pick up what I am being told is a 96 4.0 unknown condition for next to nothing. I haven't had a chance to go check and see what year. From what I have read they are the same except for a 'cam thrust plate block'. I am not familiar with what that is but if I use the head off of it as well, should have the 0630 that Cheromaniac suggested, then it couldn't cause me any issues.

Once again thanks for the help guys.

[gradon]

That 96 block and head should be good candidates for a stroker. Yesterday I finished porting and polishing the 96 head that'll go on my brother's 4.9l roller in an 88 MJ.

[Cheromaniac]

Also I know where I can pick up what I am being told is a 96 4.0 unknown condition for next to nothing. I haven't had a chance to go check and see what year. From what I have read they are the same except for a 'cam thrust plate block'. I am not familiar with what that is but if I use the head off of it as well, should have the 0630 that Cheromaniac suggested, then it couldn't cause me any issues.

As long as the block and head are good, snap up that '96 engine to build a poor man's stroker.
Parts you can use from that engine are:

Block, oil pan, head, valves, valve cover.

Parts you can salvage from your '01 engine and transplant into the '96:

Camshaft, timing set, timing cover, pushrods, valve springs/retainers/locks, rocker arms.

New parts you'll need to buy:

258 crank, 258 rods, 677CP pistons, oil pump, freeze plugs, main/rod/cam bearings, upper/lower gasket sets, lifters, 27lb stroker injectors.

Machine shop work required (minimum):

Cylinder rebore in '96 block, install new cam bearings, mill '96 head flat, lap the valves.

[SilverXJ]

Parts you can salvage from your '01 engine and transplant into the '96:

Camshaft, timing set, timing cover, pushrods, valve springs/retainers/locks, rocker arms.

The 96 block has provisions for mounting the thrust plate for the cam?

27lb stroker injectors.

Too large.

[Cheromaniac]

The 96 block has provisions for mounting the thrust plate for the cam?

Ah good point. I'm not sure about that. If it doesn't, he could simply use the '96 cam and timing set instead.

27lb stroker injectors.

Too large.

I was referring to these: http://www.fiveomotorsport.com/domestic ... itemid=299

[thraxer528]

Thanks a lot for all the info guys.

As long as the block and head are good, snap up that '96 engine to build a poor man's stroker.
Parts you can use from that engine are:

Block, oil pan, head, valves, valve cover.

Parts you can salvage from your '01 engine and transplant into the '96:

Camshaft, timing set, timing cover, pushrods, valve springs/retainers/locks, rocker arms.

New parts you'll need to buy:

258 crank, 258 rods, 677CP pistons, oil pump, freeze plugs, main/rod/cam bearings, upper/lower gasket sets, lifters, 27lb stroker injectors.

Machine shop work required (minimum):

Cylinder rebore in '96 block, install new cam bearings, mill '96 head flat, lap the valves.

Does this also apply to a 1997? The 1996 was actually a 1991 when I got there. However I have found a 1997 that I am going to call about this evening.


If this all works the same with a 1997, and I belive that it will. I will probibly try to go pick the engine up some time this week.

Once again thanks for the help.

Phil

[SilverXJ]

I was referring to these: http://www.fiveomotorsport.com/domestic ... itemid=299

Yes, and they are too large.

[thraxer528]

If those injectors are too large which ones do you suggest I go with?

[Cheromaniac]

I was referring to these: http://www.fiveomotorsport.com/domestic ... itemid=299

Yes, and they are too large.

Does it matter? After all, Phil will need to install a programmeable piggyback computer anyway and have it dialed in to deliver a "flatline" WOT A/F ratio as close to 13.0:1 as possible at all rpm. Bigger injectors might be better 'cause they won't need to operate at a very high duty cycle to deliver that A/F ratio.
Phil, the '97 engine will do fine and the same principles apply as for the '96.

[SilverXJ]

Yes it matters. With an unmodified MAP signal using those injectors it went to less than 9:0 WOT AFR. It took a whole lot of change on the Apexi to get it even close to 12.5:1. Then it had a surging idle. You want to be as close as possible to your ideal AFR to begin with prior to using any piggy back. The computer will be happier and the engine will run better. The less modification you have to do using a piggy back the better. Those injectors are just a horrible match for the PCM and a stroker.

I've tried 4 sets of injectors and the best fit I have found so far are the Jeep 53032704AB used on the 4.7L V8. They work out to about 25lb. While they still run a bit rich without modification (IIRC 11.75:1) they are a whole lot more manageable than the 27lb injectors.

[thraxer528]

Thanks. I am picking it up tonight.

Are the 677CP pistons necessary to keep the combustion ratio in check or am I able to use the original 4.0 pistons?

Am I going to have to run a piggy back cpu? OR will I be able to make it work with all the stock electronics?

Sorry so many questions I just want to make sure I do it right.

Thanks

[SilverXJ]

Am I going to have to run a piggy back cpu? OR will I be able to make it work with all the stock electronics?

If the injectors are a good enough fit and you are close enough to your ideal AFR in WOT, then you may not need a piggy back. However, you would need a wideband O2 sensor to determine where your AFR is.. or a dyno run with wideband logging.