Leakage from the front bearing seems to be a common complaint on the GMS 47 and Tower 46. Excessive crankcase to crankshaft clearance in the area between the ball bearings certainly affects crankcase base compression and fuel draw ability. Has anyone taken the time to remove the ball bearings and check the actual running clearance between the crank and the crankcase? If the clearance is more than .0015", I would be very suspicious. While air and fuel leakage from the front bearing area may not bother an engine that is not used for aerobatics, it will always show up as a poor ability to draw fuel when the nose is pointed up.

The modifications to increase fuel pressure and remove the flow resriction in the carb have apparently helped the fuel draw ability of the engines involved. I do not feel that they have got to the root of the problem however. It would be interesting to see if these engines can be flown without muffler pressure.

Before the onset of cold weather I was just starting to help a new student learn to fly with a new GMS 47. While it ran good at times, I had it flame out a few times for no apparent reason. I will be looking at it in the near future and my first investigation will be to look at the above mentioned clearance as his engine also drips fuel from the front bearing. I will report my findings in due course.