Damned A-Series Exhaust Manifold

[streetsy]

After yet another manifold gasket giving way on my trip down to gaydon at the weekend the decision was made that I must find out why. Its always the centre branch. Having removed the manifold my two main suspicions where both proven to be correct, firstly looking at the colour of the first few inches of manifold its been running lean, therefore hotter exhaust gasses. Secondly, the flange on the centre branch was not straight to the tune of 0.015", so 2 1/2 hours of filing later all three flanges are shiney and true. I'll pick up a gasket and hopefully that will be problems solved.