258 1 bbl Low Compression (71-74) Optional

Does anyone have any information or knowledge of an option for a low compression 258 6cyl engine? I have a 258 in my 74 CJ5, not sure if it's the original, but I like the feel of it. I need to rebuild and was thinking of exchanging but I don’t want to lose the feel of this engine. I've driven other 258s that don't have the same feel. The feel is forgiving if you release the clutch to fast and a tolerance lugging. Not that I abuse the engine but its a more relaxed feel. I recently came across a chart showing an option for low compression 258 6cyl from 1971 - 1975. Could this be what I have and like?http://www.amcrc.com/tech/engine.html

Thanks

 

Well, lets see. If you have the "low compression" engine, according to my understanding of the link you posted, the engine code on the side of the block should begin with a "B". "A" looks to be for the "normal" 258. So in theory, you could look on your block to verify which you have.

That being said, the "feel" of your present set up probably has a lot more to do with the engine state of tune (resistance to stall when lugging, etc.) and the condition and adjustment of your clutch. Combine that with different gearing, trannys, and transfer cases and tire sizes on the other jeeps you have driven (big difference, has a HUGE effect, along with gearing) And you can see that each jeep will be different. How it "feels" to drive any given jeep will be determined by the combo of equipment listed above.

I think it would be hard to determine a difference in "feel" if you switched between the "low compression" and the "high compression" 258 in the SAME jeep.

Rebuild/exchange to your heart's content. The "feel" shouldn't change. UNLESS you change one of the components above at the same time.

 

8.0 vs 7.6 isn't a whole lot to feel.....

 

I didn't know the precise numbers, but I figured it couldn't go much lower!