There are two things you can do to really help out one of these old 4 cyl Hurricane engines aside from normal maintenance and oil changes. Replace the carburetor and the breaker points system.
The Hurricane F134 engines came with a Carter model YF carb on them. 35 years ago maybe these things worked OK, but once they get this old I found that rebuilding the thing doesn’t work very well. I’ve heard some people just rebuild theirs constantly but I replaced mine with a brand new Solex® replacement carburetor and it has worked much better. The CJ3B site has some good information on installing these Solex® units and testimonials from former Carter rebuilders.
About the best I could do with the Carter after a rebuild was 14MPG. With the Solex® I’m getting 17MPG, no flooding, and it starts easier. The only tricky part to installing it is you will have to reroute your fuel line, and the choke cable is a pretty tight fit. Also, I found that the Solex® units you get from JC Whitney do not work, they lack the correct bracketing for the F134 engine. I finally got what was theoretically the same unit that JC Whitney sells from Willy’s Works in Arizona, but the Willy’s Works unit comes with the correct bracketing and linkages already installed.
I hate points and all the hassles associated with them. They are a royal pain in the butt. I used to have to check and adjust my timing about every 2 weeks before I found Genesee Products on the web. They sell a kit that replaces the breaker points in your distributor with a permanent-magnet and inductor setup that never wears out, and will never need adjustment after the initial installation. This is the best $90 I’ve spent on the Jeep to this point.
Installation is really easy, and it really works. I can’t recommend this upgrade enough. You can order them from Genesee Products or Willy’s Works.