Ignition timing

[jhon]

Hi all - a quick query re ignition timing. My copy of the Operating Instructions handbook specifies timing @ 0-2mm BTDC, whereas the Repair Instruction manual states 6-7mm BTDC.

Currently I have it set @2mm BTDC and it seems to run well, if a little down on power (but aren't they all - ).

Any guidance on what is correct would be appreciated. (It's a 1974 703AP model).

Thanks!

[heinkeljb]

I haven't worked out how the timing is really done, but my assumption it that they have taken a straight line measurement when using the dynastart drive pulley timing mark and the casting mark. Setting the points to open as the mark on the pulley comes to 6 - 7mm BTDC seems to work for me.

I might try altering the timing this weekend to 2 degrees BTDC using my strobe gun - in fact this might be the reason Lurch does not seem to go as fast as I expected even down hill.

The books are not clear if the 6 -7mm BTDC is actually the left hand piston (which is the one the timing is based on) - you can get a gauge which is basically a spark plug with the middle bit missing and a rod with mm marked on it which you shove down to touch the piston crown.

I really would expect degrees to be related to the pulley wheel markings, but when I got mine I checked it before I started doing anything and the marks were 6,2mm BTDC measured in a straight line between the casting mark and the pulley wheel mark - So that's what I have been using since!