In addition to my yblocks, I have a 54 Ford Naa Golden Jubilee tractor. I doubt the head has ever been off, I am the second owner and have had it about 10 years. No 1 cylinder stopped firing. Compression is fine. The push rod came off the rocker arm on the intake valve. I first thought I stuck a valve - not so. I checked the push rod, it isn't bent. Put it back and adjusted the tappet clearance. To get it to 00015 requires all the adjustment screw and leaves no room for the lock nut. Not good. Just for the heck of it, I started it. The motor runs fine (oil gets to all the rockers too) but the push rod rotates at about half the speed of the other push rods. Maybe the lifter has cratered. Anybody got an explanation for this behavior?