what gets disconnectrd before timing engine

Nothing but the vacuum advance. Don’t forget to ground the timing connector. More info is on you tube.

Site error

My understanding is that by grounding timing connectors, you eliminate signals from sensors that the computer uses to alter timing, like knock temperature, manifold pressure, etc., and that just leaves the vacuum advance to unplug.

Leave it to the professionals if you're asking these types of questions.

Too old for todays so called professionals, You need an old Mom and Pop repair shop.