how can you tell what shape the engine is in

[GTP1960]

There are three things that jump to mind - compression test, vacuum test and leakdown test.

Compression test should provide a good overall indicator of cylinder wear, condition of the rings, possible valve seat or cylinder head problems. Particularly if there is a substantial variance between cylinders.

Leakdown is kind of the opposite of compression, pumping compressed air into the cylinders and measuring leakage. Again, it will indicate cylinder and ring wear, but if there is air escaping you can also use a stethoscope to check where it's going. If you listen at the oil dipstick, for instance, you can hear if air is escaping into the crankcase. Listen at the exhaust for exhaust valve leakage, at the oil filler cap for valve guide leaks, or listen at adjacent cylinders for head cracks or gasket leaks.

A manifold vacuum test is pretty easy to do and can be a good indicator of ignition or timing problems, valve guide or seat problems, or vacuum leaks (carb, cracked manifold, etc).

If its a Spitfire, don't forget to check for thrust washer wear.