We needed to remove the enormous head of our 1939 Packard to reveal the gasket and as expected unfortunately this is what is causing the running issues.
A new gasket has been order from the US and the head is currently being machined to remove all imperfections.
We can now confirm that the head is misshapen by approximately 3/4mm which explains a lot of the difficulties we’ve been facing. Once we’ve machined and skimmed the head the new gasket can be applied.