L18 misfire problem

[Bluebird_U]

Hi everyone. I currently have a problem in that for probably the last 20km of running my L18 (twin SU copies, late style) has a constant misfire on all but a light load when running (in the garage/ driving on the flats), and of course seems to be getting worse.

I have currently checked that all the wires to the ignition are tight (condensor? on the coil was loose and sparking), pulled all the spark plugs (tan/ light grey colour), and put a multimeter across all the spark plug leads. The distributor seems tight on the mount and I slipped some sand paper in to tidy up the points, rotor and cap (still looking good relatively good/ minor corrosion).

The coil is a c6r-500 that reads 1.3 ohms (took 0.7 off for the multimeter resistance) and the ballast is 1.6 ohms - does that sound right or is one of them on the way out? I do not have a timing light at the moment so cant check to see if the timing is off which could be one reason that it seems to be constantly misfiring.

Other things that Im thinking might be causing the problem are a hose leak in the vacuum advance or the carbs or that the balance between them is out - might have to get some carb cleaner and spray it around joints/ hoses to see if it pick up. But at the moment it starts and idles fine???

Does anyone have some other ideas/ things that i have missed that I can go back over to check before I book it into a garage?

Thanks

[classicdat]

If you turn the key toward the start position, you may need to disconnect starter to confirm, does miss go away? this by passes the Ballast and increases voltage to the coil.