From your profile, I'm guessing you are asking about the '79 CJ. You can upgrade the ignition for more reliability. The upgrade is called the "TFI" upgrade. Basically, with the 258 that has the Motorcraft ignition, you replace the cap, rotor, cap adapter, coil and wire set with parts from a later model Ford 300 straight six. (AMC V8's use parts from a late model Ford 351 or 460 V8.) The parts for the upgrade cost about the same as the stock parts, and are usually easier to find at a parts store. The upgrade allows you to run a wider gap on the spark plugs which may make a bit more power, or at least make it run more smoothly. The later style cap connections are more secure than the old original type that came on the early Duraspark ignition system.

Here's one excellent write up:

http://www.jeepz.com/forum/engine/16904-tfi-ignition-upgrade.html

And another excellent link:

http://www.geocities.com/cantwait_forviolence/cj_tfi.html