74 CJ5-reciving a J-20 Engine maybe????

Well after 37 long years and hopefully plenty of abuse I'm thinking my 74 needs a new or rebuilt engine.... Right now I'm averaging 88psi of compression and well leaking oil out of every spot possible. I've been watching CL and the paper etc. for possible donors for a swap. Now I'm going to say off the bat I'm very mechanically inclined BUT I know nothing about doing a motor swap... Long story short this has been on my local CL and the price has dropped!!! So guys would this be a option... I know new mounts, drive shafts, and probably a whole lot of other stuff will be needed but has anyone heard or done this???? Thanks All

http://cedarrapids.craigslist.org/pts/2501429183.html

360 2v,400hydra-matic,2 Quadra-tracs. all this stuff is out of my '75 J-20. everything is good,the truck itself turned to rust-dust after 20+years of Ia. road salt.the motor had 'bout 50k on it(IT HAD BEEN OH'D BY ME) AND THE TRANNY WAS REBUILT JUST BEFORE REMOVAL.threeonenine3six 4nineteenfif

 

Knowing what engine you have now would be helpful to help you. If you have a 304 or I-6 now and have a manual transmission you would need a flywheel for the 360 as balance is way different. If you have a 304 then other than flywheel and possibly a cooling system upgrade if yours is marginal it should be a virtual bolt in. If you have an I-6 there are quite a few changes including frame mount on one side, exhaust, cooling system, throttle linkage, etc. but is still do-able.

 

Sorry should have added that info. I have the 258 I6 with the Dana 20 and 3 speed. I figured on new mounts exhaust intake etc but the real question is for I guess total length. I know this would be 1 cylinder shorter but I don't know about the tranny lengths. As in if the new needed drive shafts would be too short to work properly. Also is there a... availability of parts for the "new" set up??? Thanks all...

 

Hum, th400 is 18 inch long (without bellhousing) and a t18 is 11 inch long so there you got a difference of 7 inch. Add to this the adapter that the th400 and quadratrac hae something like 2 inch...so i have a 75 with 360 t18 and dana 20 t case and i dont have a very long drive shaft. So having 9 inch longer you wont have enought lenght for a good drive shaft lenght.
So if you want to go automatic there a couple of option. First you put electric fan on the rad and you advance all the mechanical at the maximun you can ( you can gain 6-7 inch) so you could be able to fit the whole thing.

Another option is to go with electric fan, gm 305 or 350, a th350 and a np205. This is a common swap into cj5.

You can use you're 360 with a manual transmission also, but you will need to get the flywheel balance of find one from a 304/t18 package. For manual tranmission find a good t18 is the best tran to put on a amc v8 because they can manage lot more power than other tran offer in cj5.

 

As I understood the OP, he's just going to use the engine.

The main problem I see with this, your T-14 3-speed won't last long behind 360 power. You need a transmission upgrade too, to make this a viable swap.

Another possibility is a 4.0L from a XJ Cherokee (and some other Jeep vehicle with the 4.0L - but the XJ is most common). This will go in without any changes to your mounts or transmission or transfer case position. Any other option, and you'll need to move the t/tc around a little and change your driveshaft lengths. You're also on the edge of sufficient strength with the T-14 and the 4.0L, but the 4.0L makes more highway power than low-end power, so IMO the T-14 would be ok if not abused. You'd have to decide whether you'd keep the Renix (pre-91) or Mopar (91-on) MPI or switch to a carburetor, but either route is do-able. Generally the 91-on 4.0L HO is the best choice, but a cheap Renix engine would get you back on the road for not much money. Or look for a good used 258, or rebuild your engine.

 

NP205, really? I recall the 205 is huge, and I suspect it would not be a good fit in a CJ. Maybe you mean NP208? I would think a NP241 would be the best fit, if the whole combo is not too long or wide for a CJ. Not that familiar with the Chevy truck drivetrains, but usually a pickup truck T-TC adapter is long, and the whole combo is way oversized for a CJ. I think your best bet is to stick with the geared drivers-side-drop transfer cases that came in CJs, ie the Dana 18, Dana 20 or Dana 300.

 

No tim the only swap i seen over the time with Gm stuff is what i said...
here what you need

but to be able to have a good lenght rear drive shaft you have to advance the engine at the maximun (almost get in contact with the radiator. I already seen that in a cj5 once before.

 

A 4.0L swap is indeed a mechanical bolt in replacement for the 258 (more or less), but the MPFI system is hardly a task for the fainthearted. It can be extremely complicated and expensive and you have to be very familiar with factory wiring diagrams. It's virtually impossible without a FSM for wiring diagrams of both vehicles (donor and donee). The best source on the web was CJoffroad.com but that forum is now offline.

 

The TH-350 CAN fit in a CJ-5 but it's really too long and doesn't address the op's original question. The other issue is not just the length of the transmission and adapter to 205 which is way long but the length of the transfer case, different u-joints, drive line mods, transmission pan clearance issues, width issues of the transfer case, and higher low range of the 205. NOT a good swap imho into a CJ-5.

Personally if I wanted to do this with minimal hassles and wanted to upgrade the transmission find a T-15 3 speed which was used '72-'75 in CJ's with the V-8. Would be much simpler. Regardless, he will have to find a flywheel for a 360 or have one balanced. A 304 flywheel is balanced wrong regardless whether it had a manual or automatic behind it.

 

If you want an upgraded drivetrain and don't mind a lot of work/cost to fit the different components in, most anything is probably do-able. But if you're already satisfied with the 258/3-speed combo and want to fix your Jeep without spending a lot, I'd vote for rebuilding the 258 or finding a different one. While I've never experienced a 360, my personal experience with a 258 and what I've heard/read about them points to them being fine engines.

 

My local engine shop told me around $1500-$1700 for a long block rebuild. My mechanic buddy say ya that about right but if I'm going to drop that money in an engine I should go v8.. now I don't really care about getting v8 power but let's be honest who doesn't want it. I guess after reading the responses I'm still at the original question. Would THIS set up be a viable option? Not taking the engine mating it to a different tranny or going 4.0... this set up....

 

Nothing much has changed. I suggest you reread the above posts.

This engine-transmission-transfer case combo is too long for your chassis. Plus it has a Quadratrac transfer case, which I would avoid as swap material. Too many maintenance issues, and a quality replacement for the problematic chain is no longer available.

Your transmission is not strong enough for this engine.

If you don't want to swap transmissions, your mechanic is steering you in the wrong direction. The 258 is a good engine, and there are a lot of inexpensive junkyard hop-ups for it (including a 4.0L swap). The CJ is a light chassis, and IMO a 258 is plenty of poop for it. Swapping in this engine is a bad idea, again IMO. But it's your Jeep and your money.

 

X2 with tim...v8 have a bad mpg is you compare to 258 or 4.0L. V8 got more power so it's asking more from you're axle...
the frame is a light frame and could break after some time under the torque af a 360.

The only thing i would plant in a cj5 with a 360 amc is a t18 dana 20 combo nothing else is you want something buit tough.

Rebuilting a 360 will cost around 3000$ (just done mine). 1500-1700$ is for a gm engine because of avaibility of aftermarket pieces.

But i dont know about the 258 or 4.0L but 360 manage to have lot of torque in low rpm and with a t18. For myself i wont go anything but v8 just because of that. Having more power than needed can be good when you drive with you're head.

 

By the same token that you found a cheap powertrain out of a J20, is it possible that with some looking you could find a cheap 258 with enough life left in it?

 

Well, this is why I mentioned the Renix 4.0L. There are lots of XJs out there, and the 4.0L HO will work fine with one of the later aluminum intake manifolds and a carburetor. They are unibody cars, and around here, rust destroys a lot of them. I presume you can convert the Renix engine to a carburetor too ... AFAIK the Renix head is basically the same as a 258 head.

Compare the 258 to the 4.0L HO (242) to the 2V 360:
HP: 110@3500 vs 185@4750 vs 175@4000
Tq: 195@2000 vs 220@4000 vs 285@2400

You can see that the 4.0L HO makes about 70% more HP - that's significant. The 4.0L torque is also higher, but at a much higher RPM than the 258. A 4.0L swap will give you something more like V8 performance on the highway, but I expect that low speed performance won't be all that different. The 360 will have similar HP, but a lot more torque at lower RPM.

 

Thank you guys!!! Page 2 answers are what I was looking for. Like I said before I know basically nothin when it comes to engines/tranny. I have been looking for a good 258 to swap in but so far no luck.As far as mpg I couldn't get much worse right now by my guessing I'm getting around 8. Lol like I said she's tired. Again thank u all...

 

If you do a carbureted non computer controlled 4.0L swap you'll have to use an electric fuel pump, the 4.0L block has no provision for a manual fuel pump. You'll need a new distributor, as the 4.0L version is controlled by the computer. A 4.2L ( 258 ) intake will not fit on a 4.0L without modification. It can be done, but it take some altering to fit. The only 4.0L carb manifold available is a Clifford unit that is about $300.

The final piece of this puzzle that is often overlooked is the alternator. All 4.0L alternators are run by a serpentine belt and controlled by the computer. You will have to figure out how to wire up an external regulator to use a 4.0L alternator. You can't just bolt on a 258 alternator as it won't work with the serpentine belt. I have an adjustable MOPAR voltage regulator controlling the alternator in my Scrambler (4.6L stroker running an aftermarket Painless injection system that does not control the alternator).

I know Tim is a fan of the 4.0L swaps, but I'm afraid he's making it sound much simpler than it actually is. Do your research before you attempt any swap, they all come with their own complications.

 

Head on over to jeepstrokers.com for good info on the 258 and 4.0 motors as far for performance upgrades and swaps. I think a 4.0 swap would be awesome in your 74 cj5.

 

You know there's nothing seriously wrong with your 258. It just needs to be freshened up. Maybe the idea of rebuilding it is worth considering.