I bought one brand new in the '70's and cycled it through two different cars; ran it on my '29 CC on a trip from Cincinnati-Dallas-Florida and back (along with a Mallory Supercoil). Worked flawlessly but I never felt that the car ran better than with a rebuilt stock ignition. Not sure that hotter spark makes much difference at 2300 RPM's. Also, with the limited RPM range, I've never seen much advantage to auto advance over manual.