Go back to basics. Make sure everything is 100% perfect. Now isn't the time to be guessing or imagining. Do your base timing setting correctly, check you're getting fuel into the cylinders. Pull the plugs and make sure they are getting wet after cranking for a while. Make sure you have good strong spark, I use a screw driver and stick it in the plug cap, I then balance the screwdriver so I have about a 10mm gap to the head. Wind it over it should throw a spark over the 10mm gap easily, don't touch the screwdriver while cranking, it can throw a spark through the plastic handle. It hurts like hell and could be the last mistake you make if you have a dickey ticker. Don't worry about the colour of the spark, that has more to do with gases in the atmosphere than it does spark voltages. If you have the clymers manual, it shows which colour wire goes to which coil. Do your tappet clearance one cylinder at a time, when the valves on 4 are on the rock, adjust number 1, when number 3 are rocking adjust number 2 and vice versa. These engines can never be 180 out on the cam, the spark system is wasted spark, which means the spark fires on 2 cylinders at a time, and the spark is triggered off of the crank. The cam turns at half crankshaft speed, so everytime the crank does one full revolution the cam does 180 degrees.
