Blue smoke problem

[crankedup]

When I start my petrol engine it emits blue (oil) smoke from the exhaust until the engine has travelled for say about an mile or the engine starts to warm up. After this warming period the exhaust is clear, the engine pulls well, starts easily now, sounds O.K and seems in general good health. The sump is not overfilled. Once the engine is warm/hot I notice backfires from the silencer on the overrun, although an new exhaust system is currently being fitted and leaks from the manifold gasket attended to. I should mention this is my 1928 Vauxhall engine.

So two possibly unrelated questions. Thanks.

[garagewidow]

blue smoke generally means burning oil,most common cause just after start up is normally worn valve guides and/or stem seals.