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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?
 
#29 ·
Okay, take your time,
Take out the bolt holding your wiring harness together at the firewall, in door all clips for it where you find them back to the trans and transfer case (but liable those, just in case. Most GM trucks used a 231 T case, so good chance the computer from the GM will hook right up, but just in case you need to use the jeep plugs, you have them labled.

About your tranny: yes you can put a jack or blocks under it, in bolt it from your engine block. Don't forget that you may have to pull your slave Cyl fork out off the throw out bearing before separating the engine and transmission. It shouldn't matter, but I've had some that for whatever reason like it out before removal.

You will keep your brake booster and master cylinder, and steering shaft.
Get your stock jeep exhaust out of the way. You may be able to keep stock power steering lines, so try to save those.

Disconnect your fuel lines as neatly as you can. And try to use the GM ones coming off the engine to where they go back to the fuel filter.

Once you get your engine out, or about out, post up any more pics of issues or questions you have.

Also, just saw this thread, lots of Q&A here: http://www.wranglerforum.com/f8/v8-conversion-questions-234412.html

Jeff
 
#30 ·
Thx! Very much apreciated. I'm just wakn up an bout to get bk to it. Ill put up more pix when I'm bout to pull the motor.
 
#31 ·
Just had a thought while turning wrenches....

Question, 98 5.7 vortec. Does this have straight or angled plugs??? Was looking a headers last night an wanted to mk sure that I get the right ones...
 
#34 ·
Hey guys, I'm startn to think a lil different rite now.
I've been pricing an looking around, I can buy a brand new, not re-man, sbc from a preformance shop near home for 1,300$ free shipping. I'm thinking of going that route instead of a rebuild. I could almost buy two for the price of just the rebuild!!!
What's y'all thoughts on that???
It's a 260hp/350ft# sbc350. Basically a replacement motor for an 80's an early 90's model trucks.
 
#35 ·
Keep in mind that that is just probably a SHORT BLOCK, no accessories, or heads or anything like that.

Also, Its a GM 5.7 If you want to save money, clean the engine up and put it in. Unless you are for sure it has a rod knocking or some other catastrophic failure, I wouldn't even rebuilt it man. If its not broken, don't fix it.

Just clean it up very nice, and take your time and go with the fuel injection. You will be proud that you did the electronics and didn't wimp out and throw on a carb like everyone else who is a sissy.
 
#36 ·
Yea the donor I was able to get is a 98 gmc z71. Got it for 200$ but oil pump went out an motor locked up. Needs a rebuild. I can part out truck r sell it to get $ bk for it but the trans, front an rear diff's r good, an ill pull all the external stuff off cuz it's all 2 mths old.
The motor I found is new, new block, heads etc.
just need to install an intake an dizzy, headers. Etc.
 
#37 ·
Also I'm def goin with FI, if I buy that new motor, im def going to look into it more cause I'm not sure if ill beable to use the vortec intake. I may have to find a throttle body injection. Still better than a carb!
 
#38 ·
I would just look into buying an older truck for all the donor parts you need. I'm getting ready to do a 350 swap I bought a 64' chevy with a 350, dana 4wd transfer case and muncie 4 speed transmisson for 500 dollars. I believe thats the easiest way that way you wont need bellhousing adapters that set you back 300 dollars.

P.s. Carbs are #1
 
#39 ·
The blocks themselves are the same. You will just need to use vortec heads. Then get gaskets and swap everything over.

Don't listen to people doing carbs. A lot of them lack the intelligence to wire a fuel injection system swap.
I would make sure you pick up a drivers drop D44 or gm 10 bolt, and then swap in the rear axle out of that Chevy.
 
#40 ·
Just finished up making my purchase!!! Found a 1995 TBI 350 with 58,000 mi on it. Everything works an runs. Shipped to my home, 600$. 450 for complete motor an 150$ shipping! Going to use dat 98 gmc in my yard for other things..... Rear end an trans mabe, if my ax15 gives up. But not sure yet. Just need to get it my jeep then ill figure out da rest!!! Lol gettn very very excited!
 
#41 ·
Okay, send me a picture of the white sticker on the ECU when you get it. I have all of the wiring diagrams from my 1995 TBI swap.

It was a pain, but it was fun and I never got any check engine lights either even though I cut so much crap out of the wiring harness.
 
#42 ·
Ok will do. It should ship tomorrow so I'm hoping to have it by Tuesday r Wednesday
 
#43 ·
Motor is almost out! Ill post up pics in an hr r so. Bout to hook it up to my tractor an lift it out with da bucket!!!
My 350 will be here Tuesday! Can't wait!!
 
#45 ·
Now it's time to clean up the frame an engine bay an get it ready for the new heart transplant!
 
#46 ·
You will need this radiator, then add a fan to it.
GPI New Jeep Wrangler TJ YJ 3 Row Aluminum Radiator V8 Conversion 87 95 97 02 | eBay

This is also a popular and recommended choice for the GM motor mounts:Chevy 283-350 into Jeep YJ Wrangler- Crossmember & Mount Kit | Northern Auto Parts

And here are the MORE bombproof most recommended motor mounts, May find a better price elsewhere but they are PN: JM400
http://www.summitracing.com/parts/mre-jm400
Also, I would recommend using the oil cooler adapter (if your TBI engine has one, mine did) and run an oil cooler up front of the radiator.
 
#47 ·
Thx for the info!

Do you think I have to have the style headers like in the link you posted or can these work???

Footwear Glass Shoe Still life
 
#48 ·
I originally was going to use the exact same headers you have there, and they SHOULD work.

The issue of why I wasn't able to use them in my V8 yj is because when the idiot who originally put a V8 in it did the mount perches on the frame rail, welded the driver side mount 3/4" farther back and caused the driver header to hit the mount. The passenger side fit perfectly, except you may have to figure out something for your knock sensor because I think the flange will sit on it or REALLY close to it.
 
#49 ·
Great! Cuz that is way cheaper than anything else i found. I know everything isn't cheap but not tryn to spend too much as I've just found out I'm having twins so I'm now on a time crunch of sort. An tryn to not splurge too much now.
 
#51 ·
No I sure haven't.

An thx!!! It was a hell of a surprise! It's great though!
 
#52 ·
Can any one tell me wtf is this box for???? I'm clueless!

Gas


It's mounted on the firewall under the bulkhead connector.
 
#53 ·
Can any one tell me wtf is this box for???? I'm clueless!

View attachment 253466

It's mounted on the firewall under the bulkhead connector.

Thats part of a UNEO Security system. Must not be very popular, or went out of business long ago because I can't find anything on the internet for them.

Also, the fuel pump you need you use is a Holey Blue pump. It is 130gph and 14psi.
 
#54 ·
Security sys......????? Dam! I searched for an hr today an came up wit nutn. Was just wondern before I pulled it out lol.

An cool thanks. I was wondern what pump an pressure I needed to get. It worked out good for u so far?
 
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