The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: stu.andrews on 28.04. 2012 16:09

Title: A7 Ignition setting
Post by: stu.andrews on 28.04. 2012 16:09
With a standard A7, 1961, with iron head, what do members set their ignition timing at, both in in. BTDC & degrees? I know it was originally 5/16 BTDC.when petrol was real! The engine has been recently overhauled.

Thank you.
Title: Re: A7 Ignition setting
Post by: fido on 29.04. 2012 15:54
The method of setting the timing is so crude I don't think I've ever got it spot on! I find it always alters slightly when I tighten the nut so I keep loosening, resetting and tightening again until  the air is suitably blue then leave it as it is. *problem* My A7SS had manual advance which was much better. You could err on the side of too advanced then if it pinked you could retard it slightly with the lever.
Title: Re: A7 Ignition setting
Post by: beezermacc on 29.04. 2012 21:50
I use a home made 'depth gauge'. I use 8mm btdc for the iron head models and 9mm btdc for the alloy heads. Not terribly scientific but they run well. If you check the metric to imperial conversions you'll find that 8mm is close to the original spec and the low compression engines are less likely to pink anyway. The 9mm spec is 0.5 mm retarded which may be just enough to compensate for the cr4ppy fuel we are allowed to use nowadays. If you find your engine pinks you'll need to retard slightly, if it runs hot and seems a bit powerless maybe advance slightly.

I find it always alters slightly when I tighten the nut so I keep loosening, resetting and tightening again until  the air is suitably blue

Might be worth lapping the taper with some fine grinding paste. If the two parts are tapped together they should 'stick'
Title: Re: A7 Ignition setting
Post by: stu.andrews on 01.05. 2012 08:58
Thanks to you both!