just to make sure top dead center is when the points are open at the fullest point when you rotate the crankshaft, is that correct ?
No, the spark occurs when the points first separate from each other, and that has to be 6 degrees before top dead center. You set the maximum point gap with the cam at its highest point against the rubbing block, but that isn't where sparking occurs. Setting the gap and setting the timing are separate operations.
Ok I may have made a booboo when setting the points the manual says this.
BREAKER POINT ADJUSTMENT NOTE
To check or adjust point gap, place spark
advance cam only. on crankshaft. Check
and adjust points as described.
(I had the key weight assembled when i set the points)
I think they are just trying to make the adjustment process easier and more accurate. It shouldn't change the outcome if you do it carefully, but I recommend you do it their way, for practice.
BREAKER POINT ADJUSTMENT D-400 SERIES
To check point gap .020, rotate crankshaft until wear block is centered on lobe of cam. MOVE CRANKSHAFT TOWARD CARBURETOR AND HOLD IN THAT POSITION
( I don't understand the bit that is underlined)
There is always a bit of slack in the upper crankshaft bearing and between the ignition cam and the crankshaft, so you hold the cam and crankshaft pushed sideways, to give a consistent reading of the points gap.
when I moved the cam so that the wear block was centered on the lobe of the cam, the hole for the key weight didn't line up with the hole on the cam so i rotated the shaft only until the hole lined up.
Is that what i was supposed to do ?
and then i should reassemble the key weight etc.
As I read it Pete, on Page 6.3 it says you adjust the points by just putting the ignition cam onto the crankshaft and rotating it until the points are at their widest gap. Then on Page 6.4 it describes a different way to adjust the points, with the whole spark advance mechanism assembled. I think either way will work - it seems you use the 6.3 method if you've taken the centrifugal advance apart, and the other method if you are just doing a routine service and don't want to take everything apart.
the yoke and weights have got a got detailed assembly in the manual except for one thing the 2 key weights have one thick arm and one thin arm. the thick arm sits on the outside of the governor collar but the thin arms sit on the inside. does this sound right because then the 2 thin arms would be touching the crankshaft.
You can probably verify the correct assembly by checking the ignition timing: with the weight pushed in close to the crankshaft, the points should just move at 6 degrees before top dead center. With the weight pulled away from the crankshaft, the points should start to move at 26 degrees before top dead center. Most likely if you put it together wrongly you won't get the correct amount of movement. Also, look at the slot in the ignition cam where the anchor screw sits in the hole in the crankshaft. It would be most of the way in one direction with the weight inward, and most of the way in the other direction with the weight outward.
I think that's enough for you to deal with for now.
thanks again
Pete
Edit
I will have a look at the seals and check for leaks
I hope you can figure out who said what above, Pete. You can check the ignition timing in several ways, but the two you can use when the engine isn't running are either look closely at the points as you move the crankshaft forward (clockwise), or hold onto the high tension wire while you move the crankshaft forward. The Mark I Eyeball method is more accurate, if your eyeballs are in good working order and it is easy to see the points. I recall using the HT lead method on an old Villiers once because the points were hard to see.
