Ignition Timing. 1962 88SS.

Like you, I see 30 in Neill, 32 in Haynes and 31 in Bacon's Norton Twins. But electronic systems follow an advance curve that doesn't flatten out completely, but mechanical advance usually goes linearly to maximum advance at about 2000(??) rpm and then stays flat. Whether my skills are sufficient to tell the difference between one degree error, I'm not all that sure. All my books also say 1/4" btdc, but that's crude with the twin with its shorter stroke than the Norton singles. Not helped by the sloping spark plugs. As far as I remember I aimed at 31.

Thats the figure I would use .I would check it on both cylinders if a mag or distributor is used. For interest I would also check on the timing disc what difference it makes if you add or subtract a couple of thou to the points setting. If you feel that there is something lacking in the performance you can tweek the timing a bit; while out on the road and easily go back to 30 degrees.A couple of thou out is enough to feel the snap has gone. While you have the disc on its worth checking that the inlet valve opening timing has an 8 degree lead over exhaust valve closing . The 88 will then fly like it should. ( a tipp from JH).

The attachment should be from Chapter 30 - The Ignition Timings as recommended in the Dominator Service Notes. It includes those SS models purchased with Higher Compression Pistons. 

It's what I do on my two singles, but in practice I always find they are OK at the book figure. Don't know about anyone else....make sure you mark it with paint at the correct figure.