[Healeys] BN1 100/4 standard build - Setting up engine timing

[Greg Lemon]

On the top dead center it was never my understanding that the mark was at 6 
degrees, thought it was at 0.  If 1 and 2 are firing and 3 and four have no 
spark it is probably not ignition timing, that should affect all 4 
cylinders, first guess and easiest is plug wires reversed on 3 & 4, if you 
did a rebuild and this is first start do a compression check if the wires 
aren't reversed, maybe a compression problem on 3-4? but that would be odd 
to be on both too, I think something is off in your ignition wiring from the 
problem as you describe it.

Good luck!

Greg Lemon (been there done that)