RE: Merlin Glow Plugs, did me right!
I have 2 OS 55's engines both on 3-D profile type planes and both with the baffels removed and use the stock NO.8 Plug that came with the engines neither have an issue running at any speed. Removing the baffels as well as a clogged nipple will decrease the tank pressure making it leaner not richer. So I have to say the needles are still some what out of whack. The use of a hotter plug to cure a midrange issues is as a rule a bandaid, however it does work so so but you pay the price in fuel consumtion.