The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: bikerbob on 16.12. 2015 15:41

Title: Degrees Ignition Timing A7
Post by: bikerbob on 16.12. 2015 15:41
I have a 1956 A7 Swinging arm model does anyone know the degrees BTDC for this model. I had set it to 5/16 with the head off and it ran OK but have since had to remove the magneto for new bearings and having a degree disc I thought it would be more accurate. I do have a chart which lists settings for A7 and 5/16 equates to 37 degrees but when measuring down the plug hole that setting measures approx 3/8. The chart I have just says A7 and relates to a 6inch con rod length, the A7 had 4 different con rods from 1947 to 1954 so maybe the chart is for an early A7. Thanks in advance.
Title: Re: Degrees Ignition Timing A7
Post by: muskrat on 16.12. 2015 18:44
G'day Bob.
 35° = 5/16" btdc which is pretty close for a standard iron head A7, 334 cam, 7.25:1 comp.
A handy calculator  http://www.dansmc.com/mc_software2.htm
Cheers
Title: Re: Degrees Ignition Timing A7
Post by: bikerbob on 16.12. 2015 19:14
Thanks for that Muskrat will give it ago over the weekend