Rebuild or swap engines

[cj7eatit]

Neuner, I was going to reply your exact response.

Well, I guess I'll try it unless someone has other suggestions?

 

[CJim7]

A 4.0 head on a AMC 258 i6 / 4.2l is still a AMC 258 i6 / 4.2l . Crank and rod from a AMC 258 i6 / 4.2l into a 4.0 is a 4.5 and with various piston's or overbore's can be a 4.6 or 4.7 so they're not the same.

No. You're right, they're not exactly the same. But essentially, you are getting the same thing minus a couple tenths of displacement. You are getting the desirable stroke out of the AMC 258 i6 / 4.2l ...which is what it all comes down to and then capping it with an upgraded head that will handle more flow. You can always bore out a AMC 258 i6 / 4.2l for more displacement.....but it's meaningless really for a little more CID.

I've done all this and in the end, ended up with a 300hp+ AMC 258 i6 / 4.2l with ungodly torque.... And that was keeping it carbed. I essentially had the same to better engine performance as the guys I ran with who stroked their 4.0L's

The only upgrades I did were cam and pistons as far as the bottom end.

 

[cj7eatit]

CJim7,
This is what I was thinking of doing....I'll try the 4.0 head swap and add a cam n springs into to it first. If it doesn't have the desired affect I'll do the below portion.... Only I think I'll get a head out of a junk yard along with the wiring harness...why not go electronic since I'm doing it anyway....

Jeep 258 Stoker kit 250hp 350 lb torque