My friend wanted to find the source of his light knock,so we fired his engine and put a stethoscope to it,isolated it to the center main area. He had a blowby issue as well,and I noticed it cranked over easy.The next weekend we went to work,pulled the pan off the '28 special coupe to take a look. to make life easy pulling the center cap I wanted to turn the crankshaft and move the crank throws level..I grabbed the throws and turned the engine,by hand,one full revolution,against compression..Now mind you,she fired cold on three turns.Its amazing how worn these engines can be and still run.Pistons so loose you could move them is a circle in the bore,number 3 ex valve fried..the rest of them done.But she ran smooth on all four.Weak,but smooth.