I found low compression today in my 91 Columbia Par Car. 20psi. I took everything apart and found a scoured piston and scuffed cylinder. The cylinder can be fixed for $40. Boring .10 to .20 over but the machine tech said I would need to tell him what the standard bore is on a 91 par car and also the piston/cylinder wall clearance. He needed these two things before he could even touch it. Does anybody have a service manual? I have no where else to look.