4jeepchick4

we're putting a 4.0 litre in the comanche instead of a 3.4 just because it'll be easier to obtain and easier to get parts for if it breaks on the trail. what is the best year for the 4.0?

5-90

Mechanically? Any of the above (save the 1999-2001 #0331 heads.)

Electrically? Depends on preferences - I happen to prefer the RENIX control setup, with OBD-II (1996-2007) being second place. I'd like to see about either adapting the GM V6/DIS OBD-II setup to the AMC six, or doing something with the MegaSquirt one of these days, to get more programmability and tuneability.

Idealised stroker buildup, for me?

RENIX block (from what I've found so far, they're a bit tougher.)
OBD-II main stud girdle
#7120 cylinder head.
1999-up intake manifold.
Custom equal-length header (I know - I'll have to fab the one I want. I'm thinking about fabbing up an intake anyhow, to tune the runner lengths and so I can park a Whipple there sidewise...)
OBD-II GM V6/DIS or MegaSquirt fuel injection setup.

Bore block to 4.000", weld and grind crank to 4.000" (or offset grind and use a custom rod.) Use a custom slug to zero deck the thing for best squish area. Clean up the head casting, maybe a light porting (if I can get access to a flowbench,) and clean up the cast surface of the combustion chamber and break all sharp corners and edges. Might run an oil spray on the bottom of the slugs to keep temps down, and run water/MeOH fog to keep combustion chambers cool and clean (I hate EGR! It's pointless, stupid, does a useful job in a shonky way, and craps everything up with carbon.)

caged

i'd say 99. it is high output, has the better intake and still a distributor engine.

but to put it in your manche, you'd need the computer to utilize the H.O., so i'd say, it's a no-go. you'd have too much electrical to change out.

you can still use the block, but use your manifolds and computer, but won't get the benefit of the H.O.

BuckB91XJ

the 91-95 4.0 HO motors are by far the best Jeep 4.0 ever put together.

Duncan1800

First, I should introduce myself. I'm Duncan, I'm new here (hi!), and I'm in the process of searching for an older XJ ('87-96) to build up.

I've had some questions rolling through my head about which version of the 4.0 to go for (because I'm not that keen on the 2.5, and I'm deadset against the 2.8), and having just seen the following words, I'm a little more curious:

So you say you prefer Renix - from what I've been able to tell over the years, most people seem to want to work around it or just swap in the later HO setup. But on the other hand, my buddy's parents had an '88 (Renix-equipped) Cherokee Pioneer for something like a decade and didn't seem to have any major driveability issues over that span.

What it boils down to is that I'm really close to plunking down money on a very clean, low-mileage '89 Pioneer (4.0 auto) and I'm hoping not to get stung. Any major issues I should look out for, or am I better off spending a bit more money and getting a '91 or higher model?

(Long for a first post, I know, but I wanted to make it count. )

nick_n_ii

Well If you ask me I'd say use a Renix block, first gen HO head and a 99 or newer intake. But that's just my thought. Oh and OBDI computer.

88fadedglory

Hi, Duncan,

I'm also pretty new here and also from CO (Canon City) but I've got an 88 Cherokee with the Renix system and even though I still don't have everything sorted out, I'd trust the Renix engine to take me cross country.

When it comes to the Peugot BA10/5 transmission also in the Cherokee, otoh, I have a hard time trusting it to get me out of the driveway . . . . . .

The only engine combo I trust better is the old Mopar 225 Slant Six.

Budd

Duncan1800

I hear you on the Slant. When I was a tiny pup and we lived in Nebraska, Dad had a '73 Dart Swinger for quite a long while. It basically was rusting apart around the engine, but that sucker never failed to crank over each and every morning.

I think I may need to go see about test-driving myself a certain Cherokee tomorrow afternoon...

88fadedglory

One of my "other" rides is a LWB 1980 Dodge D-150 pickup with a 225, the NP435 4-speed and 3.55 axle. The only emission control left on it is the PCV and at 3900 pounds curb weight and an open bed it gets as good gas mileage as the Cherokee, but then it's only got 160,000 miles on it.

Hope the Cherokee tests good. I really enjoy mine and I don't have any plans to modify it.

Budd