Mixture control question

[Moggy]

According to the Pilot's notes and Ferry Pilot's Notes for the Merlin II & III, for Cruise Max. with a weak mixture you would use 2,600 RPM with 2¼ boost. However, I've read that the standard practice was to reduce RPM further to 2,200 but even this could be stretched to 1,800 RPM for the absolute economical speed. I've been unable to match 1,800 RPM for the same reasons you stated in your post.

Hope this helps.