Can any one help, I have a kit car built with Mk 2 Escort running gear and a 2.0 litre pinto motor. Over the winter I have fitted a pair of dellorto 45's jetted for a 2.0 litre. Now my problems have started, its a pig to start, and when running I can remove plug leads 3 and 4 without making any difference, but I have checked the plugs and they are sparking well. I have been told it could be valve clearance, timing or a combination of both. The strange thing is at around 3000 rpm the mis fire almost goes.

Got any clues ?