06-12-2018, 07:40 AM
You have to remember that when Tillotson started making diaphragm carbs, they were for early chainsaws. The saw manufacturer and users weren't concerned with anything other than the ability to turn the saw on its side to cut trees. The numbering convention just went from HL1. The tiniest change, even in the holes in the throttle arm, got the next number in line. TJ