Been searching for exactly the same information‚ so similar that I wonder, John, if we already know each other but by screen names (Tailspin45).
Anyhow, I found the answers, clearly spelled out in a 1929 P&W Wasp Series C Engine Manual the San Diego Air & Space Museum holds.
Went down yesterday and used iPhone to shoot some of the pages. The images are at
http://forum.wing42.com/viewtopic.php?f=6&t=815The early Wasps did indeed have a mechanical clutch. It was later replaced with an internal; spring-clutch and then by a leaf clutch.
As someone else here notes, Wiley Posts "Stratosphere" Vega also had an external, mechanically driven supercharger mounted up on the glare shield in front of the windscreen. There was a separate, second lever to engage that blower.
Off topic a bit, but Walter Bowe's Vega, Dolittle's in Shell Oil colors, flew for the first time since 1954 about a week ago! Woohoo!
https://www.facebook.com/bernie.vasquez.5/videos/10214778990262089/