My 4A engine adopted intermittent misfiring and loss of power eight weeks ago. All electrics definitely OK, (3 coils, many new plugs, rebuilt dizzy, swapped electronic for points, several condensers, several red rotor arms, 2 complete HT sets including caps, new dizzy base plates). Despite good compression test, total engine rebuild to reset liner heights, new head gasket, figure of 8 etc. No damage to valves or head faults detected. Carbs rebuilt, new needle valves, floats OK, pistons free. This week misfire became permanent, No. 2 cylinder went out, only running on 3. (Helpful but not helpful I suppose, now I know where but not what !)
Compression test shows between 11.5 and 12 bar and no significant difference to the other 3. Several plugs and illuminating plug tester still shows strong spark, all tappets set and checked normal, all valves and springs operating normal and in correct sequence, no loose pushrods. Oil clean as when it went in at Easter, water clear, no bubbles, no overheating, no waxy stuff anywhere, no mechanical noises to indicate a problem.
HAS ANYONE ANY IDEAS PLEASE?
All suggestions gratefully received,