I am basically an unfrozen caveman mechanic. I don't usually like, or trust things that are too complicated. However, I am intrigued by the idea of the Progression Ignition HEi. I think it would be something that would work well on my '74 Cutlass 350 with an HEI unit installed, as this engine loves extra timing, at the lower end of the RPM range, but not too much total. I drive this car on long trips, including mountain driving. I think this would be better than my present system of fiddling with weights springs and vacuum advance limiters. I am a bit concerned with reliability of a system like this, but I can stick a spare HEI in the trunk if I am traveling. I am looking for real world experience with this.

 

I seriously considered one, the recent price hike and exchange made me say no thanks. Their instructions say a range of 10 BTDC to 50 BTDC. I like a few more degrees down low on a low compression iron head Olds
350. Limiting it up top is better control as weights keep advancing unless a stop is added. A few on here really like these distributors.

 

10 is just the minimum. I recently installed one and so far I'm happy with it. It's nice to be able to calibrate the table how you desire and do things like create reserve torque below idle and not be held to the limitations of a mechanical curve. My favorite part is being able to make calibration changes on the fly and evaluate immediately without having to stop and adjust the timing with a light or change springs and bushings.