The Thunder Tiger GP-42 and air bleed carburetors
I've run a number of air bleed carburetors over the years, and I rather like them. They're not overly finicky and they're easy to get set up for good, reliable performance. I own a number of Enya, O.S. Max, and Thunger Tiger engines with air bleed carburetors, and they are all fine running engines that are powerful and reliable.
Normally, when I set up a new engine with an air bleed carburetor, I simply open up the air bleed screw so that the air bleed hole in the carburetor is about half open and half closed. This is usually very close to an ideal setting for most of the engines I've run, and it is close enough to let the engine start and run reliably while I begin the break-in procedure appropriate for whichever particular model I'm running.
I've encountered a couple of Thunder Tiger GP-42 engines recently where this setting was not appropriate. With the air-bleed hole half open, the engine ran very hot at idle and ran erratically. The air bleed hole had to be mostly closed (three-quarters or more) for the low speed operation of the carburetor to be sufficiently rich for cool, reliable operation.
I'm posting this for two reasons. I want to pass this tip along specifically for the Thunder Tiger GP-42; if you're having trouble getting one to run correctly, try closing off the air bleed hole significantly to try to get the low-end mixture sorted out. I'm also posting this to hear from other glow engine users if they've also run across this issue with the GP-42, and whether the "half-and-half" rule for initial engine set up normally works well for them, or if I've just been lucky having this work so well for me with my engines.
Just curious what your experiences with air bleed carburetors have been like.