[Alan Roehrich]

It is not likely that an MSD box will drain a healthy battery while you're starting the car. A 6AL, wired correctly, won't alter the timing, it'll only process what the distributor sends it.

Have you had the battery(ies) thoroughly tested? Are you certain the timing is correct? Are you certain the box is wired correctly?

It is possible that the box is bad, but normally if it runs well once it started, there's something else wrong. If it doesn't start well AND it doesn't run well, I'd look at the box. But you need to check the wiring thoroughly first. It'll do all sorts of stupid stuff if it is not wired correctly. Check to make sure it gets enough voltage when cranking, and make sure the box itself is properly grounded, and the 12V connections are good.