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Motor Swap Question

644 views 4 replies 3 participants last post by  Hackle 
#1 ·
Hey guys I have got a couple of questions for you. OK I have a 90 model YJ with the 4.2 and the TF999 transmission. I have a 99 4.0 HO FI I6 that I am wanting to swap out. I have bought all the necessary parts or atleast I hope. Have the timing sensor, the computer, I am going to use a fuel pump to get the pressure instead of changing out the fuel tank, atleast I was told this would work. Ok my questions are as follows. Will the fuel pump work like this I was told it would but am starting to have my doubts, not toatally sure on that one. Also I haven't found and articles here that say much about the guages working. I am having some fears of my guages not working once I get the thing installed. Has anyone actually done this transplant and if so did their guages work, and if not what did they do to make them work. My last question is I have heard that you can splice a wiring kit out of a cherokee into the YJ and supposodely make everything work. Is this true or do they make a wiring kit available that is already adapted for this conversion. I am really having my doubts about this conversion. I don't want to get everything in and then have to spend a ton of money finding misc parts to make this thing work like (gas tank, new gauges, etc.) Now don't get me wrong I know there will be problems I totally expect it heck I have had jeeps long enough to know that, but just really want to know what I am getting into before I start. Ok one last thing does anybody just recommend just upgrading to 4.2L with a weber carb, and msd ignition and letting it go. I don't know I am really undecided on what to any help would be greatly appreciated.
 
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#2 ·
I have been asking myself some of the same questions. I have an 89 Wrangler with a 4.2 and Weber Carb. I can't keep it going because it keeps getting out of time. The reasons are bad timing gear and distrib. All with 180K+

I also have the op to put a Chevy 350 in my jeep.

With all the investgation I have done I am going to be well ahead of the game by just rebuilding what I have.

Our light weight buggys are made with the 4.2's and with the years worth of research I have done, I have come to the conclutions that this is the best motor for my YJ.

Now I am not going to enter any races or the like with my jeep. I just use it to hunt with and drive around town. It is my daily driver, when it runs.

The bottom line is it is less expensive to rebuild or replace with the same eq. than to use different. And certianly a lot less hassel.

Sorry for the long answer. Maybe too much info. :rolleyes:

Do all your home work. Do what is best for you and your ride based on your needs. Good luck.

Rob
 
#3 ·
The 4.2 to 4.0 swap is easy do a search on this board and others. I swapped in a 4.0 out of a 98 ZJ about 8 months ago. I was down 6 days total cost was $2400. Lots of info is available if you do a little searching. Hesco makes a harness for about $350 you can splice in the XJ harness but I am glad I spent the money for the harness. All my gauges work expect the Tach but I have not really even tried to fix it as I plan to change out the gauges anyway. You will reuse all your 4.2 sensor for the gauges
Old motor




A few links
http://www.4x4wire.com/jeep/tech/engine/fi40swap01/
http://www.cjoffroad.com/forums/forum.asp?FORUM_ID=24
http://wilhelm-tech.com/jeep/mods/40EngineSwap.htm
http://www.chrr.ohio-state.edu/~bogrees/html/tech/40swap.html
 
#4 ·
Thanks Hackle,
You have really reassured me in this swap. I think I will give Hesco a call this afternoon and see if they can help me. The only problem from what I have heard is that I have a 99 motor and their wiring adapters only work for the 91-95 motors, ooh well I will see what they have to say. I really appreciate it. Ooh by the way looks like you put in a new radiator, is that something that you found you had to do or just something you wanted to. Thanks for all the good links and pics.
 
#5 ·
The radiator I installed a long time ago as I only use an electric fan.
My motor is a 98, I just swapped the sensors to the 94 type and plugged everything in. The sensors are all the same they just changed the style of plug.
I also installed the old type fuel rail so it had the fuel regulator on the engine. This way I used my old tank and just wired in an electric pump mounted to the frame rails.
 
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