Technically, the octane shorting bar ADDS timing, when it is installed. How much depends on which "pill" is installed. While it is highly unlikely you'll be able to locate new ones, or even find any reliable source for used ones, the did in fact come in different "flavors". I have no idea what you might find in which vehicle/engine combos though.
In my case, and probably the majority of us with this motor, in this application (remember, Ford probably employed octane shorting bars in other applications), the shorting bar is a 3 degree "pill". Removing reduces timing by 3 degree ACROSS THE BOARD.
You also have to be sure it is the octane shorting bar that you are pulling out, and NOT the SPOUT connector. Visually, they are identical. Functionally, they are not. Its safe to drive with the octane shorting bar pulled. It is NOT safe to drive with the SPOUT pulled. Pulling the spout connector LOCKS timing at 10 deg advance. It will run like a dog, and you risk engine damage. It is meant for stationary diagnostic use only.
The 4.0L-OHV and Explorer/Ranger combo were designed/"tuned" to run on 87 octane, when new, and at sea level. The octane shorting bar is there so you can pull it temporarily if operating the vehicle with reduced quality fuels or at higher altitudes then normal.
I pulled the bar out for about week. It was down on power a little, but otherwise ran fine. It eliminated some pinging under load. It DID lower my fuel economy noticeably though. However, I wanted the power and the mileage back, so I put it back in.
Recently I began to experience some pretty bad pinging/rattling. It was so bad, I though it was a serious valve train issue. I decided to try running 93 octane. Big difference. Much of the "can of marbles" under load went away.
As the motor ages and accumulates carbon deposits, octane requirements can creep up, for several reasons. I suppose that "having" to run 93 octane can be seen as a "band-aid" fix as well, but I thin it a more acceptable one then cutting the , ummm, "man parts" off of your truck by permanently pulling the octane bar. The "right" way to fix it is an engine overhaul restoring to like new specs (or better), but that's not always practical.