Off Road Forums On Planet4x4 banner
1 - 13 of 13 Posts

·
Registered
Joined
·
401 Posts
Discussion Starter · #1 ·
Next week I will be starting a head swap on my 90 YJ. I have a 92 XJ 4.0 as the donor. I have done a reasonable amount of research but haven't found which flywheel I need to purchase. I know the stock flywheel on the 90 won't work. Anyone no which one I need?
 

·
Registered
Joined
·
401 Posts
Discussion Starter · #3 ·
It is an auto, so I just need a 92 manual XJ flywheel? Also, Cory told me you have done this. I may pick your brain in the next few weeks.
 

·
Registered
Joined
·
2,267 Posts
I would take it up a notch and get the auto in there right now while you are doing this. I played with the 5spd for 4-5 years and then swapped the the aw4. IT ROCKS!!! Automatics make wheeling better in my opinion. It gives me the opportunity to pay closer attention, make less mistakes and drive SO much more consistently.

There is a little bit of curiosity about this from me. Are you swapping in the fuel injection or just the head? If you are just swapping the head, then you would not have to worry about any of this... but if you are adding the fuel injection, then I gotcha. AX15 bellhousing with the CPS sensor and flywheel. OR AW4, cps, torque converter and an internal shifter for the auto.

I am not kidding around about the AUTO, it is the best thing that I ever did for the jeep. :thumb: Check out my 90YJ link for the auto swap and details.
 

·
Registered
Joined
·
401 Posts
Discussion Starter · #6 ·
Well, I am currently planning on keeping the tranny. It is a t-18 with a 6.32 first. I also have an AtlasII 4.3 and 4.10 R/P on the way. I will be crawling at 111:1. I have never wheeled an auto. Been running a manual for almost 10 years now. Why would the auto be better? What is the output spline count on the auto? I am guessing I would have to change my input shaft on the atlas. How much work is it to put the auto in? I assume I'd have to put a cooler in for it. Anything else?
 

·
Registered
Joined
·
2,267 Posts
Well, I am currently planning on keeping the tranny. It is a t-18 with a 6.32 first. I also have an AtlasII 4.3 and 4.10 R/P on the way. I will be crawling at 111:1. I have never wheeled an auto. Been running a manual for almost 10 years now. Why would the auto be better? What is the output spline count on the auto? I am guessing I would have to change my input shaft on the atlas. How much work is it to put the auto in? I assume I'd have to put a cooler in for it. Anything else?
I have wheeled the auto now for about a year and there is no better upgrade than that swap. I like to do really technical stuff and it lets me do that with alot less brain work.

Manual Pros:
Deep gears
compression braking
starter driving(running the starter in gear to really creep)
push start
its already in there
no adapting

Manual Cons:
6.32 not synchrod to the next gear
6.32 not closely related to the next gear - you basically have just one speed.... really slow
clutches every trip when you get a taller tire in there
violent engagement is harder on parts


Auto pros:
point and shoot
torque multiplication - I can push the brakes and feel the rig bite the ground harder
lots of gear options - all gears are usable in the torque range of the motor
OD - you can go on the freeway and get 16mpg (even with 38s :thumb: )
compression braking with a switch for the torque converter - see http://www.awshifting.com
manual control of each gear - same gizmo
less stalling......lots less
easy on parts with a smooth transition everytime

Auto cons:
no push start
can overheat and effect driveability
need adapter... on your rig
install work, but well worth it

Come to Boise anytime, just call and you got a driver seat pass for a day on the rock trails out here. Test it before you buy it or buy into it.


Best trailride ever was the first time I ran Carnage with twistedjack after the auto. We ran Carnage, meatgrinder and all the way out the top of extra credit after the highway cleanup and were back to town at 400pm.... this used to be a 14 hour process, dropped it to a 3.5 hour ordeal. It was all about control.
 

·
Registered
Joined
·
3,419 Posts
so, basically you get the 4.2 block, and the 4.0 head, which gives you a stroker, right?

If you start with a 4.0 rig, then all you would need to acquire is the 4.2 bottom end?

What does this do for the rig?
Higher rpms?
More torque?
More Horse?
all of the above?

Never been a Jeep guy, and am one now. (1990 Chkee)
This sems to be a popular swap.
Found a 4.2 on Craigslist, and well.... I am curious
 

·
Registered
Joined
·
401 Posts
Discussion Starter · #9 ·
The main purpose in doing this is not engine size, although you do have a larger stroke with the 4.2 block. The main purpose is to get rid of the carb and go to fuel injection. Also, this is not the "stroker" modification. I believe that ups the motor to 4.7l but I don't know much about it. Last, I have no idea what the gains are but from everything I've read there are significant gains. I am just starting to get the wiring harness in. Once it is done, I will put together a writeup on how it turned out.:deal:
 

·
Registered
Joined
·
401 Posts
Discussion Starter · #10 ·
One last thing, I have never heard of anyone switching out the block in a swap like this. I would assume the gains are not significant enough to warrant the work but I don't know.

Gripguru,
As far as the tranny goes, for now I am sticking with the t-18 but the auto is in the back of my mind. I just want to get this setup working and get some other stuff done before I undertake another project.:thumb:
 

·
Registered
Joined
·
3,419 Posts
Had no idea other than to gain EFI on a carby.
I am starting to get it, I think.
Its an EFI gain for the 258 guys, and a waste of time for the 4.0 guys as there is no gain, right?
 

·
Registered
Joined
·
401 Posts
Discussion Starter · #12 ·
Right, for a rig with EFI already there is no substantial gain but to replace the carb with EFI there are a lot of performance gains relative to off camber situations, increased efficiency, not constantly tuning etc.
 

·
Registered
Joined
·
3,419 Posts
I'll learn yet.
Promise.
The root of the question stemmed from my 7mge learning, and the fact that alot of guys put a 5mge head on the 7mge to make a stroker, (I believe Toyota actually did it themselves and called it the 6m)
Thought it was a similar process, I stand corrected/educated.
 
1 - 13 of 13 Posts
Top