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-   -   4 cyl. CJ7's (http://www.jeepforum.com/forum/f8/4-cyl-cj7s-430295/)

79cherokee 06-24-2007 08:53 PM

4 cyl. CJ7's
 
Just for curiosity, How many you guys still run the 4 cyl in your CJ7? Either the 2.5 AMC or 2.5 GM. Mine is 84 with the 2.5 amc, 4 speed, and 3.54 gears. Are you satisfied with it? I've done engine swaps before, but I've decided to leave well enough alone this time and keep it simple and stock.

twmattox 06-25-2007 09:59 AM

I ran one with that set-up for a few years. I still think that if it were properly geared (at least 4.10 with 31" tires) it would have worked just fine. Mine was geared a little too high and suffered in heavy wind or long uphills...

Oily 06-25-2007 10:16 AM

What kind of mileage do they get? I know a lot of factors contribute, just a ball park figure.

Redmanchew 06-25-2007 10:24 AM

I Just replaced my 151 GM 82'. I ran it for one year after i purchased it. It had a T-4 with a little slippy clutch in it. It woudl not pull a steady hill or on ramp very well and shifting to 4th before you topped it, forget it. I did a full tune up when i got it and replaced all the vac hoses beacuse they were completely rotted. It got a little better but on compression check it was running 110, 90, 120, 120 with spec being 150 ish if i remember.
As for gas mililage could not beat it!!!! i was running 31's with 3.54 gearing. without any speedometer correction (i was running 25mph at an indicated 21mph). I was getting a non corrected 19-20 mpg. I was figuring around 20 to 21 corrected. 9-10 gal every 200 miles indicated.

Edited: after looking at another post i was also running about 9degrees at 1100rpm on timing.

twmattox 06-25-2007 10:34 AM

Yup...18-21 consistently (depending on wind and speed factors). I ran this for around 4 years and have nearly 80,000 miles of mpg data to back...

AMC Power 06-25-2007 08:11 PM

I am replacing my 4cyl. with a 258 right now because of the power reasons. That AMC 150 really sucked going up hills! If it was geared lower, then I probably wouldn't have had that much of a problem. The engine really took a beating though! Mine burned a lot of oil and it had about 117,000 miles on it. I can't wait to try out this rebuilt 258!

gosupes 06-25-2007 09:55 PM

Quote:

Originally Posted by AMC Power
I am replacing my 4cyl. with a 258 right now because of the power reasons. That AMC 150 really sucked going up hills! If it was geared lower, then I probably wouldn't have had that much of a problem. The engine really took a beating though! Mine burned a lot of oil and it had about 117,000 miles on it. I can't wait to try out this rebuilt 258!

Same reason I swapped mine. The 18-20 mpg wasn't worth the lack of power, even with 4.10's and only 30" tires at the time. A stiff headwind and you could forget reaching 60 mph. I only lost about 2 mpg with the 258 running the same 4.10's and 33" tires and no overdrive. Should be better once I get the AX15 swapped in. There are people that rave about the 2.5 and 151, I'm not one. Dependable, sure, but that's about it.

only in a jeep cj 06-25-2007 11:34 PM

I know the MBs, GPWs and early CJs had the 4 cyl as the ONLY engine, but I do believe that when the larger and heavier CJs as in the 7s and 8s, entered the picture, the power to weight ratio of the 4 just didn't cut it. AMC had to have it due to the gas crunch of the time. I once test drove a 7 with a 4 and it was like having a briggs and stratin lawn mower engine under the hood. It feel very underpowered and just weird. But like others have said, with the right gears/tire size, the gas milage makes up for the lack of power. ......man, my 258 wasn't enough for me so I'm doing a 4.6 MPFI. I couldn't break free from the front air displacement of the big rigs I was TRYING to pass. It was sad.

twmattox 06-26-2007 03:55 PM

Don't get me wrong, the 258 is a whole lot more fun to drive (and I get nearly 18-19mpg wit it)...


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