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1937 16H Valve Timing


I am fitting the timing gears etc in my 16H, but they have no markings on them - how do I set up the valve timing from scratch please?


You need a timing disc to fasten on the crank to show the angle of the crank in degrees.

Set it to 0deg at tdc.

The inlet valve should open 27 to 30 degrees before top dead centre (tdc)

The exhaust should close 27 to 30 degrees after tdc

The crank pinion has different keyway positions to enable you to fine tune the opening and closing positions of the valves.

I hope this helps



I have 2 pre war Nortons the best method to do the valve timing I found was to  find TDC with the cylinder head off to see the rise and fall of the piston or with a timing disc and to fit the cams with the inlet and exhaust valves on the rock ie if you turn the engine both valves will move one will start to close and the other opens there are no timing marks on the gears and with the head off you can then set up the ignition timing as you can set the piston to the correct height 


I have a wd 16 h the cylinder head is cast iron number stamped on head is B4481 the bike came with this one  is heavier than the spare I have again in cast iron this has part number with BC4481 is lighter and the 18mm long reach plug fits better ie all the way into combustion chamber does anyone know anything about what the part numbers mean ?  Not the same as my old parts book 

thanks Paul t


...Gives details on how to set valve timing from scratch if the pinions have no timing marks. They're being a little disingenuous really as nobody has ever seen WD cams with factory marks on them !

The aspect of the variety of head castings is a puzzle as part numbers didn't change. There is also the aspect that the WD16H is listed with a compression plate but then it supposedly arrives at the ratio which they quote for the standard engine anyway. Obviously, in view of the scale of wartime production, there was a considerable turnover of casting patterns. Did they maybe take advantage of knowledge gained when tuning the WD Big 4, or was it the case that they redesigned the head to do away with the need for the compression plate. All these engines have to be dealt with as 'one-offs' really, after eighty years of mixing and matching.


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