[Jay Steele]

I have a 88 jeep wrangler with a 4.2 6 Cly in it. I want to put in a 350 Chevy in it. But I don't know if the transmission will fit to the 350 block

[farna]

NO, it won't fit the Chevy block. The best, cheapest alternative that will bolt right in and give about the power of a 350 chevy is a stroker six. 250 hp and 280 lb/ft (net -- on an engine dyno it would be something like 280-300 hp, 300-320 lb/ft torque, which is how the Chevy crate engines are rated -- on a dyno, not necessarily those numbers. Net hp is how an engine is rated in a factory car), bolts in. You need to buy a 4.0L Jeep six to rebuild. The 4.0L has a 0.125" larger bore than a 258 (4.2L), but the 258 has a 0.44" longer stroke. Combined they make a 276. Bore it 0.030" over and it comes up to 280 (279.8), or 4.6L. I'm running one of those now in my 63 Rambler. The 4.0L alone would make a lot more power than the 258. The figures I quoted are running the EFI. A 4V carb will run a little less, but end up costing more because you'd need more new parts. You can buy a running XJ Cherokee for around a grand, rebuild the engine, buy new sensors (CPS, temp, and O2 at least), and swap all the EFI in, then sell the body, trans, xfer case and axles to get half your money back (or save for parts -- the axles fit your Wrangler!). You don't have to do a thing to the 258 crank if you use an 87 or later, earlier just needs the nose trimmed 0.33" -- cheap when you have it turned. Your 258 should have a serpentine belt just like the Cherokee. You'll need to use the Wrangler water pump and fan, but everything swaps over to the Cherokee engine.

The only things you need to change are the cam, pistons, fuel injectors, and the balancer if you decide not to use the Cherokee transmission. Use 24#-26# injectors and a CPS relocator kit from HESCO or Advance Adapters (about $300). Which cam and pistons you use will determine if any machine work needs to be done. If you want to stick with a carb, get a 390-450 cfm Holley and a Clifford Performance 4V. With the stock 4.0L cam, 258 crank and rods, and stock type 4.0L pistons, you'll have about 10:1 compression. The EFI doesn't work well much over 9:1, so the pistons need to be dished more (machine work) OR choose a cam with a lot of overlap -- that bleeds cylinder pressure and and effectively lowers the compression ratio. Best of all, it bolts in.

For the 350 Chevy conversion you will need frame mounts, a trans adapter or new trans, new exhaust system, and a lot more work. Plus the engine. Building the 4.6L as described above will cost about the same as building a 350, depending on what parts you get for the 350. Rebuilding and installing a stock TPI 350 will result in about the same power (the 350 will have a bit more hp and torque, but the 4.6L has it at much lower rpm and the torque curve is relatively flat from 1500-4000 rpm -- mine starts pulling hard around 1200 and doesn't start to slack off until 4500, peaks around 2000 and stays flat to around 4000). My engine would be better suited to a Jeep than my Rambler wagon, but I like it! The wiring isn't a problem on a late model Jeep like yours -- unplug the firewall connector and plug the Cherokee connector back in! There will only be a couple extra wires to run.

Go to http://www.jeep4.0performance.4mg.com/ and read the Stroker links. There is also a "strokers" group on Yahoo groups that has lots of info.

I'm not against a 350 Chevy in a Jeep, it's a popular enough swap that there are kits out there, but it's a lot of work and expense when there is a better solution.

[farna]

One more thing -- a Jeep 360 (1991 or earlier Grand Wagoneer) will bolt to the existing Jeep trans and be about as much trouble as a Chevy 350. The trans has an AMC bolt pattern. If it's an auto it's a Chrsyler 998. Internal parts are the same as other Chrysler 998 trannys, but bell bolt pattern is AMC only. The 360 can easily be built to equal a 350 Chevy, but in stock form it's a bit anemic. Still, lots of low end torque, which is what you need if rock climbing. The 998 can be built to take the power, but will be costly.

If you have a four or five speed, it is a AX4 or AX5. These would be marginal behind the 4.6L stroker I mentioned. Forget a SBC 350 or Jeep 360. The 998 will be okay behind a 4.6L six, but you'll need a heavy duty shift kit and an auxlilliary trans cooler. If you get a Cherokee parts vehicle to work with, the AW4 auto or AX15 five speed will be fine. An 87-90 Cherokee (or Comanche pickup -- same drivetrain as Cherokee) with five speed may have a Peugeot BA10/5. That was marginal behind a stock 4.0L... need I say more?

You really need to check some Jeep specific boards, Dino's page is a good place to start. Also check http://www.naxja.org/forum/newfrontpage.php. Not Wrangler specific, but all the drivetrain stuff applies.

[amx82]

I'm with farna on this i have a 89 jeep cherokee with a golen 4.6 stroker kit and a avenger supercharger mine make's a little bit more than 280 hp more like 402 hp and 422 ft of torque it will melt the 33'' tire's in 4 high ( it has a np 242 transfer case in it ) and i can stomp the pant's of camaro's ,bird's and stangs light to light of coures . contact www.golenengines.com and www.avengersuperchargers.com thell hook you right up.

[Sixshooter]

What they said.
I'm running a bored .030 over 4.0 with the factory efi. Threw on a set of Pacesetter headers and a "turbo" muffler in my 89 xj. I also suggest moving the mat sensor to the cold air box. Makes a difference.
I pull a horse trailer with mine, bumping right up (maybe a touch over) the 5000# limit. Pulls great. Stopping now, that's another story...I'm in the process of swapping to rear disks to see if that helps.

[amx82]

i also forgot to mention my rear end swap i put a 96 ford explorer 8.8 in with factory disc all you have to do is buy a install kit from 4-wheel part's and i used the proportioning valve from the explorer mine stop on a dime but you have to make sure that the ford you use as a donner dosent have ABS or you'll have problem's.

[farna]

Sixshooter, you need TRAILER BRAKES, not better brakes on the Jeep! Seriously, that's your best bet. I've done a fair amount of towing with a Comanche and an XJ. I wouldn't tow to the limit like you do without brakes on the trailer. I don't own a heavy trailer, just a light utility trailer. I've towed several full size cars with a rented u-haul trailer that has surge brakes. Love 'em! I've only towed one full size vehicle with my old Comanche on a trailer that did not have brakes. 3500# car, 1000# trailer, and stopping sucked!! I like hydraulic surge brakes the best, no hookups, but electrics are fine. But do put brakes on the trailer, you won't regret it! There are disc kits for the surge brakes, they are the least troublesome. Don't know if there are electric discs, I doubt it.