Have you got the proper rubber isolating gasket between the carb and the manifold? Some of the replacement fibre ones loose their insulation properties after a while.
Don't discount the possibility of a condenser breaking down though
Heat shielding round the petrol pipes is a good idea, as is routing them as far away from the block as possible!
The Kent engine is a heavy old lump of cast iron and tends to retain its heat
Arwyn
