Bates and Edmonds Bull Dog magneto restoration

Bull Dog gets its spark back

| July 2009

Editor’s note: This two-part article is a supplement to Peter’s four-part series on restoring a 1-1/2 HP Bates & Edmonds Bull Dog, which began in the October/November 2008 issue of Gas Engine Magazine.

Having made the main body of the igniter bracket, attention then turned to the magneto and the other parts needed to complete the assembly.

Webster tri-polar low tension magnetos are known as oscillating magnetos, and are regarded as the simplest and most efficient low-tension ignition device made. This is demonstrated by the fact that these magnetos were fitted by numerous manufacturers.

The Webster does not turn continuously but operates by the armature or inductor being turned 30 to 40 degrees by the trip lever before it snaps back through the tension applied by the two springs on the front.

Different models were used on Bull Dog engines: the “M” with one magnet or the “MM” with two magnets for the smaller 2 HP engines, increasing to “J” for the 16 HP engines.

One reason for the success of the Webster was the fact that the only moving part was the armature, with no brushes or collector rings. The Webster was sold as a unit, comprised of the igniter bracket designed for a particular engine complete with a magneto. In the vast majority of cases these magnetos were set up for clockwise rotation when tripped.