What sort of crazy ignition gimmick is this?

Biggest problem was getting a tach to operate reliably. These are the reason that my 70 440-6 RR got a Jones Motrola mechanical tach. I was second owner, and the original owner (still a friend of mine to this day) had pulled the tik tok tach out for warranty, and finally jammed a Sun in there. Fits right in with friction, LOL. I took that out and placed the Jones tach up against the cutout in the cluster from the rear, and make some hardware to clamp it in place. This was a B&W face and very nearly matched the speedo.