Removing the distributor plate is a matter of taking out a few screws which hold the plate on. It's very simple. The timing will not be effected by removing this plate unless you remove the Distributor from the engine or loosen its mounting bolt. If your engine is running fine I would not mess with the timing. The easiest way if you desire, is to simply loosen the bolt on your Distributor that allows it to rotate, run your engine underload at the desired throttle setting at which you like to operate (approx 3/4 wide open) and rotate the distributor until the engine hits its peak (sounds its best). Tighten the adjusting bolt and you are there!

I believe that Moyer Marine also describes this procedure on his web site.

Good luck!