Re: Do a leakdown to tell for sure
whichever leakdown tester you buy will give instructions on how to do the test. Or search the archive or google.., there's a ton of info out there.
Engines don't always wear evenly. If you have an injector that runs lean you can do all kinds of damage to just one bore. Same with valves, if the lash isn't maintained and one exhaust valve gets tight... this is the beginning of a burnt valve seat.
But in general you want to do the leakdown to see how much blow by you have at the rings and at the valves and guides. After I burned three exhaust valves I rebuilt the head and the car runs great. 260k on the clock.