RE: HB PDP .40
I am also the owner of several HB: HB 20 , HB 40 PDP , HB 40 PDP "Blitz" and HB 61 PDP.
I use Tornado 10% nitro with 16% synthetic oil in which I add another 2% castor oil. Flying field altitude is +60m from sea level. In thease conditions the engines rev as it follows:
- HB 20 (same as Veco 19, mine from the last series bought in 1986) with OS A3 plug and a Graupner Super Nylon 9x5 propeller revs 11.000rpm on the ground, not very good idle
- HB 40 PDP Perry carb (like yours with red PDP letters bought in 1980) with OS #8 plug and a Master Airscrew 11x5 propeller revs 11.500rpm on the ground and idles at 2400 rpm
- HB 40 "Blitz" (from 1983, PDP ported, black head, black PDP letters, chromed piston with standard ring, perry pump and carb) with OS #8 plug and TopFlite 10x6 propeller revs 13.400rpm and idles at 2700rpm
- HB 61 PDP (from 1980) Perry pump and carb with Enya #4 plug and APC 11x7 propeller revs 11.900rpm on the ground and with APC 12x7 revs 10.300rpm and idles at 1900rpm
All of my figures are somehow below factory specifications and other people's tests.