4.2 vs 4.0

Sabees82

New member
I have looked with little success for comparisons of the 2 engines. Which is easier and cheaper to build or if ether are worth keeping at all. Is a v8 or 4bt conversion a better choice if i want more performance and torque...as always thanks for your input!
 

I guess a lot of depends on what the jeeps being used for? The 4.0 vs 4.2, in my opinion the 4.0 has better aftermarket support. Also fuel injection is sooo nice! I messed around with too many carbs in my short little life. If you're looking for high RPM power start looking into a V8 swap, other wise a well built(not overbuilt;)) 4.0 should be able to handle most anything if the jeeps geared right. Like i said, it all depends on what the jeeps gonna be used for and your driving style.


Atleast thats my $.02
 
My view, the carb and emissions are what made the 4.2 such a dog of a motor towards the end. but if you correct all the factroy short comings of the 4.2, there are pretty similar engines with the exception of EFI, put EIF on the 4.2, really no difference.

Now if your going to do any swaping at all... EFI V8, but also consider you will have to upgrade, trans and axles, as well as install a whole bunch of stuff (new radiator, motor mounts, etc..)

A 4bt swa is a cool swap, but beyond that I see little bennefit, at least for where I wheel. in the north east, we need a lot of tire spin on demand, I wheel with a couple of 4bt equipt jeeps, the motor is simply heavy and the lack of instant power is obvious when trying to get up an obstical.... But if you want a cool engine, great milage, plenty of torque, can't beat a 4bt for a daily driver.
 
I would do the 4.0 swap and use some of the internals off the 4.2 and make a stroker.

I did this and the engine is a beast. Just by using the crank and the connecting rods from the 4.2, the old 4.0 becomes a 4.6.

I did some other mods and I have turned the same 4.0 into a 4.8.

Easy to do and very well worth it.
 

Most people think the 4.2 became the 4.0 with electronics! Not true///
The 4.0 was built from the 2.5 engine internal specs.. the exterior bolt pattern of the 4.0 was made similar to the 4.2 but the stroke and internal parts are different.. That is how the 4.0 becomes a stroker with the 4.2 crank..
These engines are both good when used properly!
Swap! the best jeep swap is a 4.3 TBI chevy.. Its really easy and light weight!
And it puts out great horsepower for a jeep!
 
I agree with the 4.3 swap. But for ease, stay with the 4.0. Also, my stroker was put on the dyno and put out 295 HP.

All with the internals from the original 4.2. It was bored out 60 over, ported, polished and balanced. All for around $1,300.00.

I used the same transmission and TC.

It is fun to drive. :)
 
I agree with the 4.3 swap. But for ease, stay with the 4.0. Also, my stroker was put on the dyno and put out 295 HP.

All with the internals from the original 4.2. It was bored out 60 over, ported, polished and balanced. All for around $1,300.00.

I used the same transmission and TC.

It is fun to drive. :)


WOW! if ya can send me a list of what you did, that sounds like the way to go!
 

yea man that sounds pretty good. i have a 4.2 stock exept for a weber carb and it does pretty good with 33s and 3.07 gears, but that stroker would be nice!
 
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