AMC V8 in an xj

[sixshooter]

I looked on here, and searched but I didnt find anything. I have a 97, 4.0, auto. 8" lift, 35s, HP 30, 8.8, 242W tom woods shafts and SYE. It has high milage and I am considering a 304/360 AMC swap in the future. I know I can get more power from another company's V-8, however, I like the AMC V-8s, I have had 3 CJ7s with 304s an they work really well off road, oh, and I have a fresh one. Does it fit? I am concerned about the oil pump clearing. I also need to know if the 4.0 and the 258 share the same bolt pattern for the bell housing because the 258 and the V8s do. I wheel, but I am not stupid with the throttle, so I am not really concerned abotu the AW4 or the HP30. Thanks.

[xyjbeaker]

Your bell Housing Bolt pattern should match up no problem. And i belive the biggest pain in the ass with these v8 swaps is clearance issues as far ass the front of the motor, radiator, and fan. Perhaps someone will chime in on a nice fix for that issue

[redzj]

I don't really see the point. I believe the 4.0 puts out more horsepower and about the same tq as the 304 and you have fuel injection. I would also tae the 4.0 over the 304 as far as reliability. Why not stroke the 4.0 or put in a real v8?

[rock-rod]

It will fit.

The AMC V8 is no longer than the 4.0/4.2

The bellhousing pattern is the same, but the flexplate pattern may need some work. The Aw4 will have no issues (it's the same tranny used in a the twin turbo toyota supra so it's good to around 500hp)

Working around the oil pump could be an issue but it depends on the amount of lift you currently have. A remote oil filter is probably going to be required.

Why a 304 though? It really isn't going to outperform the 4.0 and as mentioned it lacks fuel injection unless you plan on adding it. If I were to do this swap and had lots of money, make it worth your while and do a 360/401 and add the Pro Flow EFI.

[Coiled88YJ]

I have a 360 in my YJ but hopefully I can help. I am having a clearance issue with the oil filter because the upper control arm mount on the passanger side comes up and hits it. I dont know if it would hit yours, but we have the same axle brackets so you may have an interferrence issue. Just depends if your axle bracket would be under the filter or not. I like the carb set up on my 360. Its the factory Morotcraft carb but it doesnt flood and runs perfect. The fuel injection would be nice, but propane is a great upgrade for the 360 or a Holley Pro-Jection. I say if you already have a fresh 304 that runs good, might as well swap it in. The swap would be easy enough I think. You might be able to weld in a set of YJ 360 motor mounts from Advance Adapters.

[sixshooter]

I used the 304 so no one got confused thinking I meant a 360 mopar. I have a reasonably fresh 360 that I would use. In terms of performance, I will be injecting it, it will have a cam, and an aluminum rad.

[Slagburn]

401 in an MJ here. I got it to sit perfectly so that a drop base air cleaner cleared the uncut hood by about 1/4 inch. The stock p/s pump also clears by about the same amount, and the water pump pulley misses the stock radiator and electric fan by about 1/2 inch. I didn't know things were going to be that close and got extremely lucky. The oil pan in that position will clear the axle at stock height or even lowered a little bit.

I used a new stock radiator for a 96 and didn't have any cooling problems running the stock electric fan next to an aftermarket one, though this MJ stayed on the street. In traffic at 95 outside temp it would get a little warm, I can't say how it would do on the trail.

A couple gotchas: the flexplate was one, I'm sure there's a stock application that fits but I never had that part. I had to weld an extension on the converter so the snout would index into the crank, then some washers on the converter bolts, and longer bolts. It vibrated a little, not recommended. The AW4 held up great for being a $100 used part with unknown history, hell I never even changed the fluid or filter.

The other gotcha is the exhaust. None of the stock manifolds or aftermarket shorty headers looked like a fit. I got a set of AMC headers and some Chevy small block blockhuggers and mated 'em. They didn't flow worth a crap (my fault) and still interfered with the upper control arms a little bit at stock height. For a 4WD application I'd recommend buying some flanges if you can find them and some mandrel bends and go to town.

edit: as far as the oil pump and filter it's all gravy- I had to trim the sheetmetal lip on the passenger side inside 'frame' rail for oil filter clearance. Not an issue where I had my engine placed