Sticky valves... Hal Nauman bought a well known 54 Manhattan. He drove it for several years. But it got where he was unable to start it. He called me in and we tried a couple of fixes, but with out success. The idea was if we could get the car started with a lot of upper lube/Marvel Mystery Oil in the gas, the valves might free up (this has worked on other cars). So we took off the head and 5 valves were seized open. I used some PB Blaster (penetrating oil) on the stems and tapped GENTLY on the stuck valves. I didn't have any success. Finally as a last resort, I used a curved jaw ViseGrips clamped on the valve head to rotate the valves as I sprayed more PB Blaster on the valve stems. The valves finally loosened up and seated. I was afraid I would damage the valve face but apparently I didn't and as far as I know, the engine still runs.