Jeep Strokers

I am introducing a new project that is a bit outside the box. The Jeep 2.5 4 cylinder and the 258 and 4.0 6 cylinder engines share a lot in common. One of those things is bore spacing. I have seen a lot of stroker builds by Hesco, Newcomer, and others have built and dyno run. The common problem is the head and its inability to flow anymore due to the design.

I propose a radical solution. The Ford small block and the 335 series engines have the same bore spacing as the Jeep engines. This project is to start out with a stroked 2.5 that will be 3.0 and modify a Ford 351 Cleveland head to fit it. The advantage of this head is canted valves, much better breathing and crossflow head design. The totally stock Cleveland head will outperform even the most radical ported Edelbrock Jeep head.

My ultimate purpose is to make a stroked 4.0 with this style of head on it. The starting point is the 2.5 because being 4 cylinder the V8 head will go on without a lot of modification. When I do the 6 cylinder I will have to cut and weld two heads together for that one.

I am also working on an adapter for the 2.5 60° GM bell housing pattern to the the Jeep 4.0, Ford small block, Chevy, and Mopar bell housing patterns. This way it will not be limited to AX-5 and AX-15 transmissions. I will post pictures along the way.

Nice!
Any progress on the head swap?

Sounds like an interesting project. Curious to see how it goes. Good luck!

Highway101 wrote: ↑January 4th, 2022, 1:18 pm The common problem is the head and its inability to flow anymore due to the design.

But we have already maxed out the valve seats per bore size. Will a cross flow head improve air flow? Or will it simply reduce intake air temp. If you want to cool the intake air charge, run water meth or e85. I think you would have to cut a billet 24 valve cylinder head to improve air flow. Run it like a 24 valve Cummins, 2 valve actuation per rocker arm.

The Cleveland head is a poly angle valve arrangement. This means that you can go as high as 53% of the bore size instead of 50.5% with inline valves. You also get better scavenge on the exhaust stroke as the intake opens in overlap. You are correct in that the current head can't make use of a larger intake valve.