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Smurf131
02-25-2006, 10:08 AM
i'm trying to devise a way of putting a 4.2L crank and connecting rods into a 4.0L block i've heard of people doing this to make a 4.7L stroker i'm wondering if anyone knows anything about it. I can put the long block together no problem but what kind of problems will i run into on the install? anyone done this before?

Nutbar
02-25-2006, 10:33 AM
Okay let's see if I remeber this one
To do this you need 4.0L block, head, and pistons 91 and newer do not use 87 to 90 4.0L parts
4.2L crank and rods 88 to 90
put 4.0 pistons on 4.2 rods
use 4.0 harmonic balancer and flywheel
both are internally balanced but you are changing the weight of the rod piston assemblies so you will have to get the crank rods and pistons rebalanced
and now with the longer stroke in the engine I think you have to shave the top of the pistons down slightly on a milling machine or you end up with about 10 to 1 compression and will have to run the thing on 94 octane or better gas
I have read a couple articles on doing this and if done right with all the 91 and newer fuel injection and a couple of the bolt on performance parts ( ie chip throttle body and header/exhaust) it is possible to get 300 hp out of it.

I think Evan the Blue still has a really good article on the build up try PMing him see if he will send it to ya
[cheers]
Mikey

bakelite
02-25-2006, 10:35 AM
http://www.bc4x4.com/tech/bryce/stroker/stroker.cfm


some info from a....uh...different site :eek:


let us know how you make out.[cheers]

Smurf131
02-25-2006, 11:08 AM
why 91 and newer?

Nutbar
02-25-2006, 11:20 AM
87 to 90 4.0L is almost identical block as 91 and newer but the heads are completely different the intake ports are in different positions and the fuel injection for the 91 and newer stuff is way a better system less problems and easier to swap into other vehicles.
the 91 and newer is a Chrysler based fuel injection and is quite reliable
87 to 90 was built by Renault and Bendix and any body that knows electrical knows that European electrical systems usually leave something to be desired the " Renix " system was problematic and only came in the little Cherokees
the 91 and newer heads also have a better intake port design and flows better making more power
[cheers]

Smurf131
02-25-2006, 11:41 AM
but i can still use my 87 block with no problems then?
just everyting else has to be 91 and newer?

Nutbar
02-25-2006, 11:57 AM
Yes you can still use the block only a couple of bolt holes change that can be drilled and tapped

Camorokee
02-27-2006, 10:16 AM
done it a couple times. Current one was built by hesco performance as they are the experts, nutbar was correct with his listings. Our 4.7 runs 315 horse and sounds wicked.

Always broke
02-27-2006, 10:39 AM
Can you say V8 alot less expensive and when you blow it up you can replace it really easy Ask Mikey [f]

Evan the Blue
03-24-2006, 11:50 PM
Here are a couple new links I've recently found on the subject........
http://www.monsterslayer.com/jeep/40Head/40Head.htm
http://www.off-road.com/jeep/new/40conv.html

I would like to do this as well..... when the old 258 finally kicks it (350K+ now) [5]

Matt
03-25-2006, 07:34 AM
yea then check out avalanche engineering they got one cool supercharger for the 4.0 stroker. with the right stuff it'll push over 400 horse.