How will an F-head do with this set-up?

i want to run 3.73 gears and 33 inch tires but i'm wondering how my F-head of 50,000 miles will like it, anyone run this set-up? i was also wondering how slow you think first gear low would be at idle speed with this set-up, wondering if the 3.73's will be too much. any thoughts or experience appreciated.

 

You will regret it.


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The more i crunch numbers at novaks conversion page, 4.10's seem to be my best bet but would that be too much? i just cant seem to find a series 4 powerlok

 

The F head with 74 hp and 33" tires. I would go 4.88's or keep the 5.38's you will be driving a vehicle with the wind resistance of a brick.

 

just to give you a idea, the newer jeeps 90's and up (Chrysler) typically run around a 4.10 axle ratio for the four cylinders. these are putting out about 120 hp. I got a 95 YJ that does 65 at around 3000 grand and this is with 30 inch tires. I don't think it would respond very well if it had any larger tires, without going to a different gear ratio like 4.88 or something.

 

4.10-1 in a 44 still requires a 4 series differential case.


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http://www.earlycj5.net/forums/showthread.php?100753-change-gears-on-a-powerlok

 

I put 35's on my F-head with 5.38 gears. And that was WAY too much tire and not NEAR enough gear. Currently it has 33 10.5 on it which is a MUCH better choice, but still needs more gear. A T90C would be a good start, but I doubt you could pull 55 mph with that setup just because not near enough power.

 

by the time you do all this gear buying and swapping you'll be money ahead just to buy a lock rite for the diff you have plus your 5.38 s are awesome. Also dont forget you'll want to repace the seals, brakes etc. when its tore down.

 

Mine was better with the 31's as well, but I love the looks of the 33's

 

Ditto w3srl. Styles come and go, but the original design engineering was pretty well figured out for what Jeeps are meant to do.

 

Sounds painful.

Try it stock first.

You may be surprised how capable a CJ with 29's and a Powr-Lok is.

 

My daily driver has 5.38 final drive with Warn O.D.
That yeilds a compound final drive ratio of 4.03.
I run 29.5" tall tires. My Hurricane is in prime condition.
On the steepest interstate grades my Hurricane has just enough HP to go no faster than 60 MPH at wide open throttle (W.O.T.)
I am specifically referring to the steepest grades found here in Missouri along the I-44, I-55 and I-70 corridoors.
These grades are very hilly but are not the same as mountain grades.

If you plan on O.D. stay with 5.58 gears.
Without O.D. run no higher than 4.09 final drive.

 

I'll most likely be stealing the 11'' drums off my 74 and swapping the two with eachother giving the 74 the 9's. i was just hoping to be able to drive at 55-60 with 33's and my f-head with a locker or limited slip in the rear.... the f-head just doesnt have it in her

 

If it were mine I would get it running, Make it safe, and see what ya got before you start making mods. Someone on here once said STOP, STEER, GO, THEN MAKE IT LOOK PRETTY. Doing 55+ in any short wheel base JEEP with marginal brakes, and steering is an accident waiting to happen.

Take one project at a time, that way you don't get discouraged with your project. save your money and do a project, save again and do another. This is how I built mine and after a while I have a JEEP that I am happy with, and it does what I want it to, and looks pretty decent. And now with 33's, 5.38 gears, F head, and open diffs I can still show up many newer Jeeps on the trail.

Just a little food for thought.

I had mine up to 55 tonight for a short distance on the flat and that is with 33's and 5.38 gears. but I have a pretty fresh engine and tight steering and good brakes.