Inline Jimmies powered our tank wagons into the early 70's. The book calls for 12 and 20. Closer than that would burn valves in a hurry. We converted to "free" valves and the 302 came with "free" valves. We made sure that 12 and 20 was a minimum. A thou or so more didn't hurt anything. And we just didn't worry about the rattling. I still break out the old Snap On tool with a 5/8 socket. I see no sense in changing something that has been working for me for over 50 years. My old 645 Sioux valve machine has a rocker refacing attachment. Refacing the rockers eliminates a lot of the rattle and eliminates false clearance readings.
