New Engine?

[Rollie]

My Jeep has a standard AMC 232 i6 6 cylinder with a T-14 Transmission . I am thinking about finding an old AMC 258 i6 / 4.2l and rebuilding it from the ground up. Bore it out, a healthier cam, intake manifold, headers, probably a Holly carb. Just soup up a 6 cylinder instead to stuffing a V-8 engine in there. Is this a good idea? Would it be worth the effort? Keep in mind this is something that I would be doing just for fun. I could work on the engine for as long as I wanted to or as long as my stock engine lasts. Just tell me if I'm crazy or not. If not, would a different Transmission be in the mix? Thinking that maybe a four speed would be a better match. I know this is probably way out there. I'm just playing around with it in my head right now.

 

[powdertwoplanker]

I was thinking of doing the same thing. But keeping my auto tranny. My thought is it would be an easier swap, plus I won't have to worry about having so much power. Don't want to break drive line parts while out wheeling

Sent from my C771 using Tapatalk 2

 

[coldair]

How much are you wanting to spend on soaping up a AMC 258 i6 / 4.2l ? I love the AMC 258 i6 / 4.2l motor they are a great motor! If your looking at getting a straight 6 I would go with a 4.0. If I knew how much I was going to spend on my built AMC 258 i6 / 4.2l I would have gone with a 4.0 and stroked it.
If your wanting to know how much I spent on mine PM me and I will tell you.

http://www.jeep-cj.com/forums/f2/4-2-motor-build-13791/

 

[coldair]

Now I'm not trying to tell you not to build a AMC 258 i6 / 4.2l . My 4.3 is supposed to be rated at 225 hp
289.9 torque at the fly wheel. I do mean 4.3 because I bored it out 0.030

 

[BusaDave9]

Just soup up a 6 cylinder instead to stuffing a V-8 engine in there. Is this a good idea? Would it be worth the effort?

.
I think it's an excellent idea. Just don't get high expectations of horsepower out of that 6.

I have had a AMC 258 i6 / 4.2l and a AMC 304 . I think they are both great engines. That AMC 258 i6 / 4.2l could roll over rough terrain at idle speed, without giving it any gas.

I like the list of mild modifications you mentioned. Just don't go gonzo with turbo, high compression or anything like that. If you want big block horsepower get a big block but then you'll be opening a whole other can of worms. A few months ago a magazine had an article about someone that got several hundred horsepower out of a AMC strait 6. It was insane but it doesn't sound like you are out to set any records.

Keep in mind the intended use of your jeep. Jeeps are made for off-road. Beware of parts that promise high horsepower. High horsepower comes at high RPMs. When selecting a cam and intake make sure you will still get the low end torque.

Good luck and keep us posted.