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location of timing gear markings on Dragonfly

Started by Reg, 11 Sep 2009 at 19:15

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Following a request from a new Douglas owner and club member, can anyone confirm the location of the timing marks on the cam and idler gears for a Dragonfly. This should be in relation to the key ways on the gears. The owner in question has gears in a highly corroded state but are usable. Thanking you all in anticipation.


Hi Reg

I have recently changed my idler gear on my Fly.
I do not know the position of the key way but when I was looking for the markings
They were very lightly marked on the gears and it took a strong magnifying
Glass to see them.
Hope this might help



Right Reg,
                  Are you sitting comfortably? First - a warning - Mr Douglas in his wisdom refers to anything on the engine as seen looking at the timing chest - so left hand on the engine is actually right hand on the machine.
       Now looking at the timing gear train - with the engine at TDC, the crankshaft pinion should have the keyway at 3 o'clock and the timing mark (in line with a tooth) at 6 o'clock. The idler has a matching mark between 2 teeth - then going clockwise, a dot in line with the 11th tooth, then going on another 15 teeth, a line in line with the  tooth.
      Now the 2 camshaft gears look to be identical at first glance, but the keyways are positioned differently (by ½ a tooth). The left hand gear has the keyway in line with a tooth, and starting with that tooth, the timing mark (a line) is between  the 16th and 17th teeth. The right hand gear has the keyway lining up between 2 teeth - going round clockwise, the timing mark (a dot) should be between the 15th and 16th teeth.
     There are no marks on the distributor gear or it's idler. A good starting point for distributor timing is 5 degrees before TDC (fully retarded)(static). Most of the Miller distributors are now suffering quite a bit of wear, and the best results are usually obtained by trial and error, and a few miles of road testing.
     If this new member still has problems sorting out the timing, get him to phone me and I will try to talk him through it.


Thank you Kevin and Eddie.

Your observations are on the way to our new member in Northumberland. As a matter of interest I notice in the Parts List and Handbooks for both the Mark series (3-5) and the Dragonfly the actual timing diagrams are the same on both with the camshafts sharing the same Part Numbers. Not having a Dragonfly gear train to hand I have used a Mark gear train and found the oservations on timing marks made by Eddie on the cam gears for the Dragonfly are in exactly the same position on the Mark gears.
Again many thanks to both of you for responding. Reg.


Thank's al lot about the Information about the location of timing gear markings. I am restoring a MK IV Douglas (7260/4), which has been equipped with worn out sport camshafts. From the Douglas Club I got standard camshafts to fix the machine. Although everything seems to be assembled quit correctly,  the valve timing on the left and right side was rather different. On the left marked timing gear I had to go one tooth back to get the correct timing, although I counted each gear as Eddie suggested. I can't imagine the reasons. However, this post was really very helpful!