I did a compression test and the results were: piston one 150psi, two 150, three 135, four 150 pistion 3 seam rather low, So i started it up and took no 3 spark plug lead off and it made no difference to the running. Then i took the head off, the head gastket was fine, the bore was in good condition too. when i was turning the engine over by hand (with the head off) it had a slight hard patch is that normal?