I can't tell from the photo, is it a manual for Red Wing brand gas engines? They were built in Red Wing, MN for marine and stationary use, I see them fairly often at shows in Minnesota. There's a little history on the company here:
http://redwingmarinemuseum.com/history2.html
It is...[ ]...I will post more photos this weekend.
Stuart: As promised, here are some photos!
Unfortunately, the condition of the manual - more accurately a catalog, I suppose, is only fair, at best. It's legible, but soiled pretty badly in places (something was splooged into the middle of one of the pages and it soaked through to all the pages before and after it in that same spot). Still, interesting read, and some cool images. See Pic 1 (cover) & 2 (logo zoom).
The early pages include a Foreword with a brief history of the company, their Guarantee and Terms, and a long detailed description of the Thorobred motor, component by component. Then there is a page for each motor, from the Model KK (7-8 H.P.) - see Pic 3, to the Big Chief Special (110-150 H.P.) - see Pic 4.
Some of the motor images are fairly clear. See Pic 5.
The last page is an ingeniously designed schematic, one figure of a motor, with dimensions keyed to a table of all the motors. See Pic 6.
As best as I can interpret, my gut instinct on it being from the 1930's looks pretty prescient. According to the website you linked, they dropped 2-cycle engines in the late 1920's for 4-cycles, and the line and range they describe is exactly what is in this catalog. Pretty cool to see that Zane Gray had several boats with Red Wing Thorobred motors.
Nuggets too!
) may be in order.
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