RE: Hirtenberger .61 with a sliding piston carburetor
Bax,
Am I in error about the length of the OS glow plug?
Now I'm not questioning your operational success with the OS plug, but did it fit the combustion chamber? I often ask why wear a size 10 shoe when you have a size 11 foot?
Engine designers spend a lot of energy trying to make the transition from the glow element to the combustion chamber as smooth as possible. You will have noticed that in the sub 2.5cc class of engine they often use a glow head insert. Or for bigger engine you will see the Nelson type glow plug/head with its chamfered seal area used instead of the 1/4x32 glow plug.
Also what was the fuel that you used (as the agent for HP) were the OS #8 worked so well for you?
All the best,
Konrad