Jeep Strokers

Any reason I couldnt/shouldn't run the below setup?

4.2L 3.895" stroke crank
4.0L 6.125 rods
KB 9956HC (4" bore, 18cc, 1.433 pin height)
Skim down piston pin height to 1.398
Compcams 68-232-4
FelPro 9076pti .051 head gasket

-.021 deck clearance
.030 quench height
10.76 SCR
9.21 DCR

Any input is much appreciated.
Kris

You may have to go thru several blocks before you find one that will take that much over bore??, and even then keeping it cool will be a challenge.

I have a 98 and 91 block. I read somewhere the late model blocks have thicker walls. I already have standard .060 over pistons. Was just thinking of using the 4.0 rods and saw those pistons, they are a better price than the IC944. I guess I could use the 4.2 rods and the .060 pistons if that would be a better idea

IH 392 wrote:You may have to go thru several blocks before you find one that will take that much over bore??, and even then keeping it cool will be a challenge.

Even if you find a block that'll accept a 4" bore, I'd be concerned about the longevity of the engine with the cylinder walls reduced to the minimum thickness after a 0.125" overbore. One overheating episode could result in a cracked cylinder and it's goodbye engine.
Stick to a safe 0.060" maximum overbore.

Cheromaniac wrote:One overheating episode could result in a cracked cylinder and it's goodbye engine.
Stick to a safe 0.060" maximum overbore.

This. This is more threatening than the typical wear of a high mileage engine. I went with 0.060" overbore due to serious wear and cleanup issues but if I had to go any further, I would have picked another block and started over. 0.010-0.060" is the safest range and it's where parts are available without getting expensive. There are many reasons to stay within these bounds.

This combo will work. Get your 91 block sonic tested, as these have been the blocks( 91-92), from my experience , that are thick enough. I havent had any overheating issues, on the street or off-road racing.