IO-360-A3B6D to A3B6 Conversion

[MichMooney201]

23 hours ago, jetdriven said:

Prop governor for the A3B6 is a different part number because the drive pad ratio of the A3B6 is different as well. Any given engine RPM the prop governor input RPM is different.. hence the need for the different governor model number. 

The difference is the drive gear ratio from Lycoming, .850 on the B6D to .861 on the A3B6.  Max prop governor RPM is 2340 for the A3B6.  I used West Coast Governor on this and went to the T22 governor for the A3B6 where the B6D uses the T17.  The issue is either in the mounting of the cable or in how the governor is clocked.  You would think this is a straight forward issue but it isnt.  The armature supplied with the governor where the prop cable attaches can be oriented only one way. The mounting screw that attaches the armature to the prop governor shaft shows up 2 different ways, however, depending on how the hole in the armature is tapped that takes the socket head cap screw.  The armature only fits on the governor one way because there is a recess on the back side of the armature where it is mounted to the prop governor shaft to hold a clip.  The set screw that clamps the armature to the prop governor shaft goes through a clearance hole on one end of the armature and into threaded hole.  Depending on what way the clearance hole and threaded hole are made on the armature, the socket head cap screw head could be on either side of the armature.  Now add into the mix the $150 2 inch stamped sheet metal part from Mooney that is made to fit over the armature and you have the problem.  The stamped bracket is made in the shape of an "L", and the foot of the "L" is designed to sit on the side of the armature where the threads are, not where the head of the screw is; no other option, the bracket is directional.  If the head of the screw is on the side where the bracket foot sits, it obviously interferes with the bracket because is cant sit flush against the armature.  The use of the bracket changes completely how the governor is clocked, which is set from the factory or repair shop.  So I got an armature with the screw on the wrong side, so the bracket doesnt fit, and the unit is clocked incorrectly.  You can clock the governor by loosening the 6 screws on rotating the unit, but that makes a difference how the rpm's show up on the tach based on where its clocked and other convoluted criteria.  None the less, its a high speed taxi trial and error to get the correct setting with a rough idea on where it should be from West Coast governor.  As advertised, the prop governor is the root of all evil in this conversion.