Yes gap is set at 55. They actually say you can open it to 65, but I figured I would stay with 55. All it is, is a hot coil and performance wires. Read here: http://www.performancedistributors.com/jeep4.0.htm At anything other than idle its smooth and runs like a scalded cat. No misses, no nothing, just smooth sailing.
As for the timing, its controlled by the computer. (no vaccume advance)You cant even adjust the dizzy on a 4.0. it has a tab on it that the hold down bolt gos through that wont let you turn it any. It only goes on one way.
