I've just fitted new pistons and rings to my 3MB 2 1/4 petrol engine. At the same time I had the head refurbed and set up for unleaded. I haven't run the engine yet but did a compression test (cold/wet)
1 - 125psi
2 - 125 psi
3 150psi
4 150 psi
Looking at the results you'd think head gasket...