[Healeys] High speed miss - CARBS?

[john spaur]

I still have a misfire at high speeds and at low speeds when I accelerate.

The timing seems to be set correctly and the fuel tank, pump, lines, 
filter, needle seats and float chambers are clean. The plugs and 
points are gapped correctly.

The carbs were rebuilt but I don't believe the piston/suction 
chambers are to factory specifications. The carbs are original and I 
am wondering if that is why I am getting the misfire (it is not a 
back fire through the exhaust).

Has anyone had similar symptoms that were cured only by replacing the 
carburetors with new ones?

TIA

John Spaur
'62 BT7