I own 2 Sears Penske's, one is the standard type and the other has the dial on it for total advance. If I test the two, side by side, there's a difference of about 1 or 2 degrees. Wich one is right, I dunno. For my cars, 1 or 2 degrees isn't going to make a big difference. But if I was running nitrous or a supercharger, that would be a big difference and I would look to a top notch one like a Snap on or one sold through Summit ect..
You can do anything you want to......ONCE!
aka "my 66 coupe"
Hale Boppe comet shot off my roof. See you can use 100 iso at night with no flash!