I had heard that but since my original OMC factry service manual said to, I thought I would check it both ways. Readings were identical. I really hope someone can verify or dispute what I was told about the 91 having compression relief ports. I cannot recall what he siad as to what the reason was.
I was told by whom was billed as a master OMC tech that the 1991 VE70TLEIE had compression relief ports that would cause a compression check to read 10-15 PSI below actual. Mine runs pretty good, as far as I can tell. I have only owned this one a couple of years but given its age I wouldn't...