Jeep Strokers

Hi all!

I have a 1979 CJ5 with a 258. I'm getting pretty tired of running a carburetor. I started researching options for converting to FI which led me to dropping a 4.0HO from a junkyard in there, but I learned that people were not terribly happy with the 4.0's torque - which is how I ended up here!

First question: Will I simply be able to use the block, head, pistons etc. from the 4.0 with the crank and connecting rods from my 258?

Second question: is there a specific year range of 4.0 engines that would be preferred? I know there are TONS of 4.0s in the junkyards around here. OBD-I preferred for simplicity and emissions control issues.

Third question: Am I missing anything? Is it really this easy?

Thanks,
Matt

I know OBDI is simple, but OBDII ECU's are tunable through reprogramming. You could get even more drivability out of a stock motor simply through an ECU tune.

mburgess00 wrote:First question: Will I simply be able to use the block, head, pistons etc. from the 4.0 with the crank and connecting rods from my 258?

Second question: is there a specific year range of 4.0 engines that would be preferred? I know there are TONS of 4.0s in the junkyards around here. OBD-I preferred for simplicity and emissions control issues.

I think your best bet is to find a cheap 4.0L YJ or TJ to use as a donor vehicle and then you can scavenge everything you'll need from it. Just avoid the '00-'01 models 'cause those have crack-prone heads.
You can use the your 258 crank & rods to build a stroker out of the donor 4.0 engine but I suggest you have a machine shop check the cylinders for roundness and taper. On a high mileage engine they may be out of spec and a rebore may be necessary, in which case you'd need a set of aftermarket stock replacement oversize pistons.