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5.7 Vortec swap

52K views 210 replies 19 participants last post by  whiskeywiz 
#1 ·
The old 4.2 finally crapped out..... I was able to pick up a 98 gmc z71 as a donor truck. Motor isn't running, which I will rebuild, tranny an all the rest of power train is good.
What do I need to keep off of the donor to put into my yj?? I know the computer for sure, but besides motor, what else????
Going to be my first motor swap so any advice would be great! Anything I should look out for or tricks to mk it a lil easier???
Also I'm going to attempt the 350 rebuild myself. Any tips?
 
#160 ·
I can't remember how the GM harness is wired off the top of my head. I know they probably didn't give you an Alt plug due to the wide variety of options that you can use. GM uses a few different types of alternators.

They have a 1 wire (old style) which probably would be an easy way to go, but make sure that you search for wiring up your type of alternator to be sure.
 
#161 ·
Yea, the one I have is a one wire plug on the alt. I was just curious as to see how to hook it up. I thought it was just strait to battery, but not sure.
 
#164 ·
Ok guys, I'm a lil stumped on the alt wiring stuff. I've searched an got my self confused with the stuff I looked at on google.
My plug on my alt has 1 wire coming out of the plug. Then I have my battery lead off of the back. Where does the plug wire go?? Does it go to the ignition r does it go bk to the battery?
Need help!
 
#166 ·
Ok. Ill go threw it again. Ima need to re print da ones I got cuz I left em outside on my truck tool box an the dew got to them. Lol too much shit goin on!
 
#168 ·
Slow... I've been so busy with wk an other stuff here at home, I haven't had much time to wk on it. I actually pulled wires today, an wired up my motor an ECM.... Now I just got to get the gauges an dash wired bk up, install my fuel pump, an get me a rear driveshaft an I actually mite beable to start an drive it!!! Lol
 
#169 ·
Well finally makn more progress..... Takn more time than I would like but it's still moving....
Got all the old jeep wiring out this weekend an started re wiring with new switches an also started Mkn a new dash plate.

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#170 ·
Looking good man, you had the exact same idea as me it seems. Once I had my dash all apart making a flat dash is going to be super easy and look 20x better imo. What did you paint it with in that last pic?
 
#172 ·
Yea I do agree... An it mks it a hell of a lot easier to wire the motor an gauges lol. Some 20+ yr old jeep wires can be a pain in the ass. So I figure I would just put new since it was torn apart.
The paint I used is some krylon spray for plastic. Had bought it to spray the dash when I first put new gauges but figured if it stuk to plastic it would hold dam good to aluminum lol
 
#173 ·
Im going with a new 18 circuit chassis harness from speedway. There pretty cheap and will surely make the wiring a breeze. Plus like you say 20+ yr old wiring in a jeep has been hacked up many times... Then it will give me extra circuits for down the road
 
#174 ·
Yep that's what I also did... Used fuel inj. connection harness an added a 100 amp +/- bus bar that I had extra from re wiring my boat... Figured it would wk good being a marine bus. Now I have a few xtra terminals to add some goodies....

Auto part Technology Wire Electronics Electrical wiring


If ya look down by the shifter, up against the fire wall, you can see the bus I added...
 

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#176 ·
Thx man! I know exactly what you mean about the life stuff!! Lol with two lil ones on the way, I'm about to get a big kick in the ass by life! Lol
 
#177 ·
Well, the correct radiator an new intake will be here today! So finally, ill beable to start an let it run for a bit. Hopefully at least!! Ill post pix of my dash an stuff later tonite!
 
#179 ·
Thx man, i need the encouragement lol, I'm getting kinda frustrated with the whole thing. I'm so busy with work an stuff, I barely have time to turn a wrench anymore.
 
#180 ·
I know the feeling. I had a day off today and spent all day re doing my exhaust, and putting in a new Prothane transmission mount and re- checking all the bolts from originally installing my lift kit.
 
#181 ·
Well finally!!! Woo hoo!!! Got my cooling system Finally in an piped in, fuel pump wired an piped. Now just need to drain the dam tank again......;/
Shitty, crappy, junk ethanol fuel.....



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But, before I drain the tank, I think ill just put a jug of gas underneath an prime up pump to ck for leaks........ An of course push the start button!!!!!!! It's still open header but it will b ok to run for 5 min r so.... Lol ready to hear it run!!! Sob it took a while, but I think it's well worth the headache!
Now just need to bleed clutch, measure the length for new rear drive shaft, build it at work an have it balanced, then finish wiring up gauges in dash, an ill finall beable to drive it outta the shed!!! Dam excited!!
 
#184 ·
Yea gettn real close finally! I was able to start it an let it run for a lil while. Wanted to mk sure that I had no coolant leaks, or oil leaks. Now all I go left is to bleed clutch, drain an clean tank, an build my driveshaft at work, then I should beable to take her for a spin!!!
Wish I could post a short video, she sounds mean!! Lol
 
#185 ·
Hey guys, I've got a question about my rear driveshaft. I'm needing a shaft that is real close to 15" running length.... A stock length yj shaft for a auto tranny is 14-7/8" running length... Do you guys think I could run that shaft??? I've got a buddy with a parts jeep yj, with an auto tranny. Said I could have the shaft..... But want to mk sure it will work
 
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