Conversation has moved into springs and retainers but I'm still thinking about the cam thing...
Interesting thoughts on the extra 1/2 a pony, I'm going to dive in to an early HS and later LH195SP/HSSK55 (have both) and measure everything for myself but my teardown bench is blocked up until after the holidays.
The larger base circle, was that across the (small frame) cam production or just the 37040 cam? I can't remember if I heard that cam was an OHV part that made it's way into later production HS(SK) or designed originally for the flatheads.
Wouldn't surprise me if the 5.5hp was just a sticker or an actual hp increase from a combination of other tweaks but 10% is a big gain for production engines.
