on a stock gm hei distributor (454 engine) there is a box coming off the cap that says tach-bat.
it appears the yellow wire is the battery and white is for the tach. just how do you attach the tach wire ? do you just tie in or is there a connection at this point ?
thanks.

Yr of engine and dizzy? Should be a connector. Older ones use 56 series connectors, newer ones use weatherpack connectors.

Ours was the older spade type connector in a '72 Chevelle with the factory tach. The tach wire had a common female connector. Worked fine.

your tach has 4 wires... black to ground, red to the ign on fuse block. blue to tach where the batt/tach post is..then white to a hot for the tach light.. at least thats mine.. phil