Having recently swopped carburettors I took the opportunity to check how well the joints between the carb and cylinder head were mating.
I noticed a pronounced ridge of about 3mm where the inlet manifold mates onto the head. This may only affect performance at high revs – but it is not ideal.
It seemed as if the manifold needed lifting a little which would be a quick and simple solution to centre the manifold to the head. So I slotted the inlet manifold mounting hole and repositioned the manifold which cured the problem.