375/16 Monobloc

[Bynorthsea]

I have had this carb set up and running ok on my Dragonfly as a replacement for the original 375 that on which I could not get the slow running sorted out. How I could have missed it I just dont know but when I stripped it again to remove the crud from a newly commissioned tank I noticed that it has a 1/16" drilling from an eccentric groove in the bore and clear through, so there is a permanent air bleed, slow running only requires a quarter turn out. Does anyone have experience of a carb with this feature, do I just live with it or put a peg in the hole and retune?

[eddie]

I think you'll find this carb was originally intended to be fitted to a two-stroke engine (maybe a 175 BSA Bantam). Another mod on 2 stroke Monoblocs was a choke block with the top of the spray tube cut at an angle.  Evidently, these mods were an attempt to get cleaner running on 2 strokes with piston controlled timing - i.e. inlet open equally either side of TDC.

Providing there are no other mods, blanking off that drilling should make the carb the same as the original D/fly carb - I wouldn't attempt to fill the slot (as the filling would do damage if it worked loose and got drawn into the engine).

  Regards,
                 Eddie.