Timing up ‘58 Dommie

From your picture Steve, it looks like you have electronic ignition (Boyer)?

So, you just rotate the distributor (after loosening the clamp) until one of the screws on the rotor is showing through the hole in the backplate with your engine at top dead centre. This will be close enough for you to start the engine and should it spark just a few degrees before tdc at idle speed.  If the engine kicks back when trying to start, then retard the timing a little and try again.  You may find your distributor is in an inconvenient position after rotating it and finding the screw and then you will have to alter the chain and sprocket inside the timing cover by a few links to get it right.  There should be a direction arrow on the 'top' of the distributor denoting which way it is rotating.  Once the engine is running you can rotate the distributor in the same direction as the arrow to retard the ignition and visa versa to advance it.

I like to set up my ignition timing on the road and never go by what the manual states as it depends on many different factors - compression ratios and petrol quality.  Firstly, experiment with the rotation of the distributor until you can achieve reasonable starting without it kicking back.  Then, out on the road with the engine fully warmed and in top gear at about 35 - 40mph, open up the throttle and listen for 'pinking'.  If you don't hear picking then your ignition is probably too retarded and needs to be advanced.  If on the other hand, you hear loud pinking, then you are too advanced and the ignition needs to be retarded.  Once you get to the point of very light pinking on opening the throttle at the speeds mentioned above, retard the ignition very slightly and the timing is then set for life and you're good to go :) - unless you then use some crappy fuel that is!

I set my timing  much like Bob Matthews  method  ( I have points)  and go by feel as much as anything.  But thats after 60 years of  absorbing what feels right.  I expect you would be  comfortable with something more tangible .  You could set up a timing disc  on the  drive end of the crank  and get the  crank  at the full advanced timing  position  then  mark the alternator rotor and stator with two marks that align and use these in conjunction with a strobe light as you would with any modern bike. You could put these marks somewhere around the upper part of the alternator and cut a hole in the outer case for a grommet  to give access  that would allow you to check and strobe without removing the cover (if you are not too fussy about orriginality.) Or just strobe with the cover off. Once its running well you could use the orriginal dissy clamp to make small adjustments.After about 50 years you will just know when its right !!.

Attachment might be useful as a starting point.

Bob mentions 'a hole' in the Boyer plate, but there is two holes! You need the one that shows the screw 'BEFORE' it passes the coil.

On my web site I have a drawing of a small plate (it's under Lightweight timing aid!) that can be fitted under a stator bolt and it makes a pointer for ignition timing.

Have fun.

The Ch47 document is in Word, so if you open it in such it should all be clear. Does your PC have the options to open in other formats?