I bought my 68 E type at a salvage yard so I don’t know it’s history. Also several things around the engine were missing and I have never had the engine running. From several clues, my guess is that the car may have spent around half its life unused sitting in a garage or barn.
Early on I tested cylinder compression and found only about 80 psi on 4 cylinders and even less on two. As a minimum, I was sure I had some bad valves so took the head to a good machine shop and had it rebuilt
The head is now back on but I haven’t connected the cams yet so can’t test compression. So I did a leak down test and found lots of leakage but none coming from the valves…
The obvious conclusion, I assumed, was that the piston rings are worn so I took off the head again and removed the pistons.
Everything I can see now and/or measure is in very good condition;; pistons, cyl walls, bearings and crank.
The point of this ponderous story is to ask how can I tell if the rings are bad. I put top ring in the cylinder and measured the end gap, which is between 0.80 and 0.90 mm. Is this a good thing to measure and what do these numbers tell you?
Of course I have the apparent blow by But what else, if anything, can I measure?