1999 Jeep Wrangler TJ 4cylinder To Chevy 350 Engine Swap

Posted in Perfomance Parts

I’m going to swap out my 4 banger for a Chevy 350 turnkey crate engine and I need help. Any guidance, references, opinons, or personal experiences would be helpful. I would like specific guidance for parts. Everything from what radiator I should use, to what transmission I should go with, or what will be my gear conversations. Please help me out!
I don’t plan to put a roll cage on there. I’m going to use this as my daily driver, and a weekend warrior. Thus I would like for my jeep to handle highway speeds as well as pull in the dirt. I already have a 3″ inch lift kit installed, and I’ll be running 35″ tires. I don’t plan to do all this myself….I’m more or less looking for a list of exact parts to buy that have worked with other projects. Any references for a decent mechanic in the Fort Riley, KS area would be nice.

There are 6 Answers for "1999 Jeep Wrangler TJ 4cylinder To Chevy 350 Engine Swap"

    1. Chief Joe Heap'o'turds says:

      Just make sure that you’re a good welder.

    2. victor h says:

      4 core radiator. is it a 4 wheel drive? you will probably have to change the gears if its a two wheel drive to a better highway gear what rpm do you want to run at 70 mph? How will you drive it rough or daily driver? 350 trans or 400 turbo would probaly work. Don’t blame victor for these answers this is his wife ang. What are the specs on the motor?

    3. b says:

      If you cant figure out beyond buying the motor, then maybe your not the person to do it. I would yank the body off. Do the motor , trans , suspension, drive line, brakes, You are going to have to improve your 4 wheel drive system to something that will handle a V8. Plus a lift kit. Lot of work, lot of fabrication and welding. Like motor mounts and a roll cage. Let a pro do it.

    4. scott v says:

      Jegs or Summit make have the kit you need, I’ve seen that done before and it makes for one sweet ride.

    5. 4x4guru says:

      they make motor mount adapter kits for this conversion and as far as trans goes use a well built 700r4 if you want overdrive and if you dont use the turbo 350 also the transfer case that you have the 241 is a good case buy the adapter for the trans that you end up using and for the radiator get an aluminum one that’s made for your jeep they make them to fit your application all of the adapters you will need should come from advanced adapters they are a little high but quality stuff also the gear ratio in the 4 banger is probably 4:10 so that would be great

    6. JeepGuy says:

      How big is your budget for this project? Here are my recommendations and a few web links. This can get pretty pricey, buy you’ll have one SWEET Jeep when you’re done!

      Transmission: If you have a manual, it’s the Aisin AX-5, and it will not handle the torque of your Chevy 350. I recommend a NV3550 5-speed (good, found in 00-04 Wranglers), or NV4500 (a beast truck tranny that fits in a Wrangler). If you have an auto, again I’d upgrade. I recommend a GM “Bad Boy” 700R4 Overdrive Automatic.

      Transfer case: The NP231 that you have now is likely adequate. If you want to upgrade, I recommend a NP241OR (the transfer case out of a Rubicon), or better an Atlas II transfer case. I have 4:1 low range in my Rubicon, and I like it. It might be too slow for you though, in which case go with 3.0 or 3.8 in the Atlas (if you go with a Rubicon TCase, you get 4.0).

      Axles: You have a Dana-30 up front and a Dana-35 in the rear. I recommend swapping out both axles for Dana-44’s. Even stronger options are available, Dana 60’s come to mind, but as a daily driver you are not likely going to spin your 35’s in mud at max RPM’s, so Dana-44’s should be more than adequate. 4.10 gear ratios will likely be tall enough for regular highway use and the 350 should be able to deliver plenty of acceleration with 35″ tires. Go with Superior or AlloyUSA Chromolly axle shafts, 35-spline if you can afford it.

      Drive Shafts: The stock front shaft might be adequate, but an upgrade to a stronger unit is never a bad idea. You definitely want to upgrade the rear shaft to a CV or double-u-joint design. I recommend Coast or Tom Woods drive shafts.

      Misc: You’ll need a new wiring harness, computer, radiator, and exhaust. I don’t have recommendations, but whomever you are buying the engine from can likely offer suggestions.

      Also, be prepared to spend a lot of time getting your setup to fit into your Jeep, then troubleshooting the little nit-picky details (vibes, engine performance, etc.). It will be a lot of work, and quite expensive, but your Jeep will be unique, a blast on the highway, and a monster on the trails. GOOD LUCK!!!