My six cylinder solution to my 4cyls towing anemia - JeepForum.com

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post #1 of 22 Old 08-12-2015, 06:43 AM Thread Starter
fishadventure
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My six cylinder solution to my 4cyls towing anemia

I have two YJs: my 89 DD and the 91 project. In the course of things I have two 4.0 donors, a couple of 258 cranks, and a 70s 258 block.
The 91 will eventually contain a stroker with the "heavy" 12 weight crank, but that's a long term project than I'd hoped.

The DD on the other hand has a perfectly good running TBI 2.5 without enough horsepower for how I am always towing stuff. So the 258 with a standard crankshaft and a 4.0 head is looking pretty attractive. And inexpensive on the relative scale.

I need a cam... The wear pattern doesn't look great on the one that was in the block. So new lifters, too, and while I am at it, timing set makes sense. I notice there is an OMIX cam for like $130, but I am concerned with how it will wear. I see a Comp Cams kit for like $330 on Amazon which is still not insanely priced. And I have always had an affinity for anything Crower or Edelbrock. Edelbrock has a basic cam and lifters for like $180.

I am inclined to order the Comp Cams kit or the Edelbrock. So after reading a bunch of cam threads this AM I decided to look for input because the only reason the OMIX looks appealing is cuz a stock grind will probably suit my needs, but a little torque and HP peak 2500-3000-rpm would be nice. But I certainly don't want a high rpm power band. There isn't a lot of real spendy difference between the OMIX and the Edelbrock $50ish on Amazon.


How many old threads actually convince *you* to read all 36 pages? http://www.jeepforum.com/forum/f12/length-envy-build-thread-629700/
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post #2 of 22 Old 08-12-2015, 07:07 AM
crackedcornish
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I'd go Edelbrock over Omix for internal engine parts any day

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post #3 of 22 Old 08-12-2015, 09:40 AM
jsawduste
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If the 4.2 you have now is a 81-90 your running
190 @ .050/.403


The 91-95 4.0
197/424


Comp 68-115-4
192/416 Intake
200/416 Exhaust


Melling MC809
197/424 (same as 91-95 4.0)


If it was me I`d look at the Comp or the 4.0 grinds


Get good lifters.....Not parts store imports....and break the cam in properly.


Edlebrock leaves much to be desired in there cylinder heads. I`d wouldn`t get overly excited about a camshaft.
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post #4 of 22 Old 08-12-2015, 01:36 PM Thread Starter
fishadventure
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Quote:
Originally Posted by jsawduste
If the 4.2 you have now is a 81-90 your running 190 @ .050/.403 The 91-95 4.0 197/424 Comp 68-115-4 192/416 Intake 200/416 Exhaust Melling MC809 197/424 (same as 91-95 4.0) If it was me I`d look at the Comp or the 4.0 grinds Get good lifters.....Not parts store imports....and break the cam in properly. Edlebrock leaves much to be desired in there cylinder heads. I`d wouldn`t get overly excited about a camshaft.
I momentarily forgot there was someone here who committed all the specs to memory

My 258 block is 1978.

What got my attention on the Comp kit is that it had lifters and bearings. I am a little partial to the idea of the cam manu providing the bearings and lifters.

I also have a running 4.0 from a 98 XJ I forgot about. A real short cut would be to pop that in if I found a TBI intake and comp. But it wouldn't be new.

Re: Edelbrock- but I trust their metal. Not going to wear out too fast. At least that used to be the case...

How many old threads actually convince *you* to read all 36 pages? http://www.jeepforum.com/forum/f12/length-envy-build-thread-629700/
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post #5 of 22 Old 08-12-2015, 06:47 PM
jsawduste
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Assuming your 258 is unmolested it should have the 12 cwt casting #3214723 with a 64mm nose. I save those 12 cwt cranks for "special" builds. Most often use the 4 cwt crank from an 81 + or a Scat.


The 98 XJ would bolt in. If your simply running a carb then an adapter plate could be made for the (4.0) intake and the carb switched over. Just an idea........Or you could use your old intake on the 98 with a little grinding at the dowels.


Keep in mind your 98 will have a 54 mm nose on the crank. You will need a spacer for the HB. If you go that route then let me know. I can hook you up with a spacer through Russ Pottenger.


Intakes can be had for cheap. In fact from RockAuto you can buy a brand new 99+ intake for around 130 bones. The engine itself will need to have the sensors switched to OBD1 parts as the terminals and connectors are different. Don`t forget the flexplate/flywheel with the notched for the crank sensor signal.
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post #6 of 22 Old 10-24-2015, 07:15 AM Thread Starter
fishadventure
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Well. This might seem haphazard and I appreciate the help and info so far. It will be useful on future stuff, but right now I am changing directions slightly. I have a plan in motion to save time since summer is past and its 26 degrees F this morning. Winter is here.

PLAN: I am saving out the 4.2 for a future use and just using a '98 XJ 4.0 straight up since it runs good and doesn't need rebuilding. I have a pre-95 OBD1 4.0 intake and a selection of AX15s on hand. Also have a '94? 4.0 MPFI computer. I am swapping out my rusted 2.5 frame with a 4.0 frame so motor mounts are covered as well. And I've got a bunch of driveshafts. So mechanicals are covered.

Where I am going to need help is that I am essentially swapping in a '95-or-earlier OBD1 MPFI 4.0 into a '89 2.5 TBI setup. So computer harness and engine harness aren't so simple. Got some great info http://www.jeepforum.com/forum/f12/l...e-pics-668796/ from leans thread, but my bookmarked 4.0 swap thread has become obsolete with many dead links: http://www.jeepforum.com/forum/f12/4...63/index2.html

So I had a thread saved with stuff from Queue I can't seem to come up with detailing some stuff for the '89 2.5 TBI to 4.0 MPFI swap. Weird cuz I thought it was my thread??? Whatever. If anyone has that please post up the link for starters.

FIRST QUESTION: should I piece back together the 1993-ish 2.5 MPFI harness and swap it into my '89 or deal with what remains of the '94 4.0 harness and swap that in?

This is my DD so I plan to have everything lined up before I go for it. Fairly likely I'll even install a pair of 3.73 D30/D35 axles I have along with the motor, driveline, brake lines, fuel tank, and steering and simply deposit the tub on a roller. That way I'll only have bolt-ups and the wiring debacle in question to deal with. I want to have the harness mods done and prepped of course. Then I'll have a running '89 2.5 in a frame with driveline for sale...

How many old threads actually convince *you* to read all 36 pages? http://www.jeepforum.com/forum/f12/length-envy-build-thread-629700/
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post #7 of 22 Old 10-26-2015, 06:30 PM Thread Starter
fishadventure
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bump
QUESTION: should I piece back together the 1993-ish 2.5 MPFI harness and swap it into my '89 or deal with what remains of the '94 4.0 harness and swap that in?

How many old threads actually convince *you* to read all 36 pages? http://www.jeepforum.com/forum/f12/length-envy-build-thread-629700/
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post #8 of 22 Old 10-27-2015, 06:34 AM
Que89YJ
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Fish I am confused on what on have and what you want to do.
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post #9 of 22 Old 10-28-2015, 06:45 AM Thread Starter
fishadventure
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I am going to put 94 4.0 YJ computer and put it in my '89 2.5 to run a 98XJ 4.0 motor with YJ 4.0 sensors.

I have a previous owner cut up '93? 4.0 YJ harness and a '92 2.5 MPFI YJ harness to choose from.

I am assuming the '92 2.5 MPFI harness is a better place to start. Wanting advice and/opinions on which and maybe some double spots might be averted. If the '89 were MPFI it would be a no brainer...

How many old threads actually convince *you* to read all 36 pages? http://www.jeepforum.com/forum/f12/length-envy-build-thread-629700/
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post #10 of 22 Old 10-28-2015, 06:50 AM Thread Starter
fishadventure
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Quote:
Originally Posted by Que89YJ
Fish I am confused on what on have and what you want to do.
Ya sorry for the confusion. I *wanted* to do other things but time, money, and logistics with the season and garage space have convinced me to just be very very very simple since this my DD. I just need a few more cubic inches for towing. Plain 4.0 will do it. And I probably won't have to buy anything.
I've just started and stopped too many times and have to work and have life and sleep now and again.

How many old threads actually convince *you* to read all 36 pages? http://www.jeepforum.com/forum/f12/length-envy-build-thread-629700/
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post #11 of 22 Old 10-28-2015, 07:03 AM
Que89YJ
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If you have an unmolested 92 harness that is the way to go. Set up the harness before you start so it just drops in.
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post #12 of 22 Old 10-28-2015, 07:06 AM
Que89YJ
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The 92 will be closer to your harness and you can pull and add to the harness to make it work. Add 2 injectors and lengthen the wires where needed.
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post #13 of 22 Old 10-29-2015, 06:38 AM Thread Starter
fishadventure
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Quote:
Originally Posted by Que89YJ
The 92 will be closer to your harness and you can pull and add to the harness to make it work. Add 2 injectors and lengthen the wires where needed.
Thank you thank you thank you. That's what I was thinking but no experience to base it on... The 92 harness was cut off clean under the dash so the fix is diagram free.

Q: I haven't looked yet but will I even need to change the bulkhead connector and stuff under the dash? (I thought you answered this for me a year or so back but I can't find the thread???)

How many old threads actually convince *you* to read all 36 pages? http://www.jeepforum.com/forum/f12/length-envy-build-thread-629700/
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post #14 of 22 Old 10-29-2015, 07:42 AM
jsawduste
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No, the underdash is the same for both 4 and 6.
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post #15 of 22 Old 10-29-2015, 08:10 AM
Que89YJ
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You have to move pins on the bulkhead but the harness can be left in tact. I just took a quick look and there are at least a dozen circuits you will need to deal with between the 2. Gauges, blower, feeds, etc. changed between the years.
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