Was there any lead in the petrol / paraffin / TVO used in all sorts of tractors, before, during and after WW2 ? Many of these machines worked their nuts off, pulling hard and getting hot without their valve seats falling apart - I am in the process of helping a friend to get his pre war Fordson running, so I know a bit about these type of machines as well - the Fordson has compression, even though the head may never have been off - how come? There is no lead in diesel, either and the heat in these engines is much greater than in petrol ones, yet you never hear anything about their valve seats. Our Enfield racers have run many seasons of racing on methanol [no lead] and their valve seats have never been changed and are fine [unlike the big ends, which do need replacing sometimes!]. B.W.