The Fordson Tractor Pages Forum

My 1938 N is fitted with a Lucas SR magneto which does not have an advance & retard mechanism and I have had to replace the Champion C5 plugs with W14's.
I am now finding that I am suffering pre ignition with a pronounced knock at low engine speeds.
Is there a colder or more suitable grade of plug that I can use to overcome this problem? I get the impression in these days of rationalisation that the W14 is a sort of one size fits all solution and you have to like it or lump it.

You can alter the timing a little by playing with the points gap , wider advances , tighter retards .

Thanks TMC for the reply. I will do as you suggest and see what happens. I didn't about using the points gap to alter the timing, but it is a good idea.