Is the bolt pattern on the block the same? Also what is the difference between the output on the engines?

Ask Luis... the guy with the axle.

The BH bolt patten is the same. The 4.2 BH doesn't have a CPS (crank shaft position sensor) mounting hole to pick up 4.0 flywheel pulses.

The difference in engines is how ya build 'em ...!

Typically the 4.2 has more torque ... longer stroke ... and the 4.0 has a shorter stroke but bigger bore.

Best application ... 4.0 block (for bore) + 4.2 crank (for stroke).

BHousing: Use a 4.0 with MPFI CPS mounting and fly wheel or use a 4.2 BH and get an MPI kit's dampner plus it's CPS mounted to the oil pan bolts.

Search fer more ...
:flipoff2:

by output I mean the output shaft. What is the length of each, and what is the spline count of each. I ask this because a friend of mine has a 4.2bellhousing mated up to a T-19. The main goal here is to have a 6:1 first gear

there is no output shaft on the engine.

It's an input shaft to the tranny...


Now I'm confused... he already has it mated up... wha'ts the problem?

Oh Oh I can answer this, I just changed my clutch a couple of weeks ago, the output from the 4.0 (like most engines) is a flywheel. bolt the right clutch disk to it, and any tranny will work (assuming you can make the bell housing fit)

chad

and can find the right pilot bearing


So, what's the problem again...???

THe pilot bearing on the 4.0L is slightly smaller than the 4.2. You can either spend the $15-20 at Advanced Adapters for a custom one. Or if you have acess to a way of turning it down you can do that.

The A-A bushing NEVER fit right. they need to be turned down, too.
no big deal, just stick a stock CJ bushing on an arbor and hold it to a piece of sandpaper for five minutes

There is also an overall depth difference in the flywheels. The older 4.2's, which are properly called 258's, use the Ford type starter, and the flywheel extends approx. 1/2 inch back. The newer 4.2's, built by Mopar, use the same gear reduction starter as the 4.0's, and have the same depth flywheel as a 4.0, but with different "tone notches". These tone notches will work on a earlier Renix 4.0 fuel injection.

If you wanted to put an older CJ's bellhousing and tranny behind your 4.0, you will have to change your cps, and re-locate your clutch fulcrum forward for proper geometry. This is easily done by drilling the stud where the ball sits, and screwing in a GM stud. Or just drop the 500 clams on a AA housing.

Actually I am running a 98 4.0L in front of a stock '76 bellhousing and tranny. I built thew relocation kit for the CPS for the harmonic balancer. I am also still using my stock 258 flywheel and starter. I was told that you would have to shim the starter. However mine is working perfectly. I also did not change anything with my clutch linkage. I will give it a look when I get back in town.

You already have the starter and flywheel matched, so you should be good. Also, since you used the 258 flywheel, you clutch should be fine. The problem occurs when you use a 4.0 flywheel with the 176 bell-housing. Then the fulcrum should be shimmed.

Your set-up sounds great! How does it run?

It runs like a scalded DOG! Fuckin sweet man. By far the best mod I have done yet. It is stumbling a bit right now becuase I have not ordered a fuel regulator yet, and I am running the non return fuel rail. So I am ordering a regulator with a return and mount it next to the tank. Man it is all the engine that my little 5 needs. O yeah not to mention I noticed that on my 3rd day of driving it that I took something into the oil pan off the road and punctured it pretty good so now I get to drop them pan and weld it up. I also kept the engine OBDII for diagnostic reasons.