Originally Posted by nickdz
I've got a little different view of the 151 "Iron Duke." My jeep is a 1980 CJ-7 that used to have a 2.5L GM 151 "Iron Duke" mated to an SR4 4-speed tranny. I've got to admit that I was very fond of the "Iron Duke" for its reliability and economy (I ragged the heck out of it trying to get it to move the jeep and it kept on going). And I do agree with its overall performance being a direct function of how well the engine is maintained and the vehicles overall gearing. In my case, the jeep was lifted ~3 inches and had 33's. The engine was supposedly overhauled 10K miles ago and was in good condition, but gearing was not condusive to this set up.
I was not able to keep up with traffic on the highway and found the lack of power a severe problem in everyday driving (to the point of being unsafe).
When it came time for me to do something about this lack of power, I opted to swap out the engine and tranny for a more powerfull set up. While the "Iron Duke" seems to have somewhat of a faithfull following, I personally would not recommend it. I would suggest a 258 maybe. Those are relatively inexpensive to find a rebuilt one.
Just my two cents.
Good info and very correct...when you change your set up with mudders..lifts and low gearing differentials; ie: for climbing abilities), I greatly agree with you when it comes to driving on the highway.
As recent as yesterday..my son and I drove 183 miles in his standard cj 7 jeep 151 iron duke, and couldnt contain a safe speed over sixty miles per hour..with the large dirt/highway tires
we had on. They hold 30 lbs. of air max filled. But we found her
doing (everything) the other jeeps did, with exception of large steps where the big boys with lockers and very low gearing out did us as we watched in complete amazememt; their awesome
abilities climbing steep steps over a foot high!
Can you tell we just came back from the rock trails in Randolf, Kansas?
Any whoot..the iron duke is not an agressive climber..BUT if you want to drive it back home 183 miles..you know to take careful concideration when trailing and NOT ABUSE it. We stayed in 4 low lock in first gear, and found NO trail we could not climb
stated as: (WALKING HER UP), VERY steep hills over a block long.
While we enjoyed the hell out of it, and experiance non-the-less,
Yes it would be nice to beef her up, and you can.. with the following;
Lockers...reverse spring lift, taller tires, and with that set up, you can follow and even OUT do the big boys.
The 2.5 liter engine is great with this combination.
visit our site at http://members.cox.net/aphelion79/jeep
look for the link of trails visited..you will see a brown TJ with a 4 cylinder that out did the big boys in every single climb..and it is a four speed manual.
His jeep is like a freaken tonka toy wound up , and let go, and will climb anything in its way...even an almost vertical climb over 40 feet high.. I witnessed it last night!
It's not what a jeep should do, it's what you want to pay to have it do..because ANYTHING is possible with posi rear and front axels.