Ignition Timing & modern Fuel

[Martyn Goodwin]

I think the greatest thing about the BT-H mag is that steel rod that locks the mag at the correct position so you can time it to your figure, so simple so easy compared to all that taper tightning rigmarole and allowance for drive train movement.
Its just amazing that it was never thought of before on coil or mag but then we are talking about the design department of the Lucas Prince of Darkness empire. designers of that pressed steel whirley gig of wear the ATD

I seem to recall from my hands on experience with a "new" BT-H that with the steel timing rod in place you could still rock the motor back n forth by around 3 degrees in each direction. Could help explain the variable results some folks have with them?

 

[derek]

Does anyone have a graph for the standard advance curve of the original ATD?, or the revs at which max advance was achieved.

 

[Martyn Goodwin]

Does anyone have a graph for the standard advance curve of the original ATD?, or the revs at which max advance was achieved.

Lots of information here
http://www.brightsparkmagnetos.com

look in the FAQ section. In summary the Lucas ATD starts advancing around 700 rpm and is at full advance at around 1200 rpm.

Martyn

 

[tatty500]

Don't forget these are half engine speeds and angles, and that the picture is for a 12deg unit while the Vincent is 17deg advance.

 

[derek]

MartynG. Is the ATD advance range of 700-1200 rpm, The engine rpm or the ATD rpm??

 

[clevtrev]

MartynG. Is the ATD advance range of 700-1200 rpm, The engine rpm or the ATD rpm??

Engine RPM would put it about right.

 

[Martyn Goodwin]

MartynG. Is the ATD advance range of 700-1200 rpm, The engine rpm or the ATD rpm??

Not sure, I think its engine speed; anyway, re-read my earlier post #63, and the info at BrightSpark

 

[Martyn Goodwin]

Ran for a wile with 32 BTDC then switched to 30 and have finally settled on 28 Yes 28.

Martyhn

 

[redbloke1956]

Ran for a wile with 32 BTDC then switched to 30 and have finally settled on 28 Yes 28.

Martyhn

Why 28 Martyn?

 

[timetraveller]

And we need to know the engine type, squish bands, twin plug heads, compression ratio etc. Cheers; and although this is not the right place I think that David, our Australia based ex-Vincent employee, is a real treasure and a wonderful source of information. I, for one, do not care about his punctuation. Keep going David.