F-Head 3.73 combo?

well i was going to put 4.27's behind the F-head till i found out the rear was junk got a set of 3.73's donated to me today for hauling a carR) so my question is has anyone ran 3.73's behind a F-head134 and how did it do,looking to be able to drive this jeep on and off road,i really liked the 4.27's but they are hard to come by here and i really dont want to spend the $ on having the gears setup or replaced,maybe later on that,just currious on how the 3.73's will do behind the 4 banger

 

Sounds like a big mistake to me. Those little motors were designed to work best with the low ratios, like 5.38. I'd suspect that 3.73's would just be too high of a ratio to work with an F-head. Might be able to go down the road OK, but it would probably be a bear to get it rolling and would likely downright suck off-road. Like changing clutches? And stalling on hillsides?

Just my opinion. It might actually work and you might like it. You might cuss a lot too.

 

my pickup has 3.08's,does well off road but it aint woth a nickle when it comes to pulling a heavy load,and thats with a v8,may just swap the rear out and unlock the hubs and give it a test run around the farm here and see how it does,not into rock crawling or any thing like that but do enjoy using the national forest roads,and with gas as high as it is i would like to be able to ride this jeep to work and run errands as well,it is the only non v-8 that i own,and the only other 4wd besides my pickup

 

Yeah, I think you'll find your options limited with the F134. Try to go faster with different gearing and you'll run out of power. Remember that power is basically torque times RPM. For the same torque, cut the revs by 13% (1 - 3.73/4.27 = 13%) and the power goes down by roughly 13%. You need all the power you can get from a F134 to overcome the wind resistance barrier ... from 45 mph to 60 mph the resistance increases by 44%. This is a significant barrier, and you need all available power to get up to speed.

 

i have a 1970 cj5 f134 that came with 4.27's,and i believe it came from the factory that way,considering the mileage and that i bought it off of the 2nd owner and he bought it in 1977 with 32000 miles acording to the title,so i dont believe anyone swapped anything around given its history,just a shame that the rear was junk,it seemed like the perfect gearing what little i drove it i dont know guys i am gonna experiment with this, f134 puts out what around 90hp? i really dont see where there should be a power problem with 3.73's its not that heavy of a vehicle,and has more tourque than most 4 cylinder engines today,prob got more tourque than a ford ranger wiyh a 4 cyl,and i am sure they aint runnin gearing in the 4's or 5's

 

New an F-134 puts out 72hp I believe.

 

Im sure it would be a gutless wonder !!!!

 

just refered to the old chiltons,72hp is correct@4000 rpm's but here is the kicker maximum torque114 ft lbs@2000 rpm's

 

poor little thing who,d wanna winder that tight?

 

give it a go, it's your Jeep. Let us know how it works.

 

I have v6 t86 3.73 and i wish i had 4.27 or even 5.38s... and i have 3X your torque. it would be almost 30mph in first gear for you.
4cyl wount have the guts.
http://www.csgnetwork.com/speedcalc.html
it works ok for me with 300 ft/lbs but with maby 100ft/lbs it would be a dog.
But just my opinion.

 

you guys are prob right,if the v6 has around 300 ft lbs torque, not that big a deal to swap one rear out and see, gonna have to reaplce a main leaf any way,if it dont work i will have my rear out and can regear as i saved the 4.27 ring and pinion out of the junk rear

 

well thats good to know,i was planning on using the trans out of the jeep with the 4.27's,thanks glenn

 

well just thought of a place that sets up rearends,and gave him a call,for $200 labor and a box of parts"already have on hand" i can use my 4.27"s and that is what i wanted in the first place,heck it aint worth $200 for me to even try it,if i get it setup wrong its gonna cost me more than that, drop it off and come back and pick it up,be ready to bolt in,cant beat that with a stick may can recoupe the $ out of the 3.73's