RE: Numbers for ST G21/35 DDD head
I ran a glow K&B 4011 on glow with 10% nitro, and then on diesel. I kept the glow plug lit until it was warmed up and running nicely. In both cases it turned an APC 11 x 5 at 9,700 RPM. It had a venturi and ST NVA. I turned the needle in 1 1/2 turns to get best RPM with diesel. I ran a Drone with a MAS 11 x 9 at 6,700 RPM. Put a Drone glow head on and ran it on 10%. It ran smoother at 6,700 RPM. I actually had to turn the needle in a little to get best glow RPM. I understand that is an idiosyncrasy of Drones.
So there!