Hi Again:

       Thanks for all of the replies!

       One thing that caught my eye was the effect that smooth intake porting vs. rough porting of intake areas reminds me of motor heads of the 50's performed on their engines to increase power.  The idea was to polish the inside surfaces of the intake manifolds to a very smooth finish.  This was to increase fuel/air mix into the cylinders.  This was done wiring the manifold onto a tractor or grader wheel after placing some gravel into the manifold.  After a week or so of this treatment, the inside of the intake manifold would be polished  to a smooth finish resulting in less drag.  Did this work? Who knows but it was the cool thing to do to your mill.

      Later in life, I noticed that intake manifolds were cast with many small bumps on the interior. The fuel droplets would "stick" to a smooth surface hindering the mixing of the air/fuel mix. Could this be wrong?  I later learned that the bumps were intended to help anatomize the fuel charge on the way to the cylinder. Did this improve anything, I do not know but...

                                                                                                                  Be well my friends,

                                                                                                                  Leomat

 

Typical length of the stationary inlet 'manifold' on a model engine after the jet is what, 10mm?

And since most are single cylinder vibrators I can't see that fuel droplets sticking is an issue.