An enigmatic Douglas engine, with no known date, and that gave 70 hp, existed under the name of "Bearcat".

-This is a modified Ford-A engine that passed from water-cooled to air-cooled, as we can see in the attached figure.

"Douglas-Ford"

From Appendix 9: We now show an advertisement that mentions some details:

"Douglas (USA) advertisement"

-It is clear that they offer the plans to build parts and convert the cooling system from liquid to air, and other details.

-In the latest information the name "Bearcat" was used. In the photo we see that the ignition is double and with two Delcos.

"Best view of the Douglas, exhaust side"
 

-This model gives 70 hp at 2650 rpm.

From Appendix 10: We have found out that this engine was used on the Knight Twister model KTD-2 in 1937.