The twin plug conversions for airhead BMWs specified less advance than standard.
Nor can I think of any modern engine fitted with twin plugs as original equipment. I'm open to correction.
OK TT wait til I've reached a conclusion, and I'll have a shot at measuring where it's firing.
David, I'm only on single plugs. Peter Appleton says he's running 40 degrees on a more sophisticated ignition computer and thinks he could go higher, and if the timing marks are right, I've past that and still going.
My thought is, why do conventional systems stop advancing at 4,000 rpm (ish)? Why should the advance be the same at everything over 4,000 rpm? Could it be that there is such a wide range on my advance curve that I can keep advancing it to suit 5, 6, 7,000rpm but not be over advanced at lower rpm.
Yep,
Keep going Howard, you are exactly on the right track, and bear in mind that many of those obsolete and worn ATD's reach full advance at a lot less than 4000 rpm. John
Still going John. I'm at about 45 degrees now - I say about, because I ran out of scale long ago. Starts first time, ticks over like a metronome (the one with the blue hat and fishing rod), plenty of torque and power from pilot jet to full bore, doesn't kick back and I can't make it ping nomatter how I try. I have just put a very open silencer on and increased the jets to 260 as well, but it's never gone this well before - 100 mph (true) sitting up (touring bars) on an incline - and that's on an A road with no distance to build up speed. If I go much further, I'll have to quote the timing ABDC not BTDC.
H
OOps......... I meant private runway, not A road.