motor locks up at 60 lbs. compression

by jay
(marysville, wa)

I bought a 1986 Bayliner conquest from a guy for a fairly decent price I drove it from Seattle to Everett on one engine on the port side assuming that the starboard side just needed a starter or as I was told that's all it needed so I start tearing into the motor I put on a starter I get it to crank over so I decide to do a compression test when I put the compression gauge into any of the cylinders and crank it over it builds up 60 pounds of pressure and the n the engine locks up so I hit the pressure release on the gauge crank it over again until about 60 pounds and it does it again in any cylinder why is this I don't understand Motors much but people who do and I've brought this to their attention do not understand it as well please help fYI the guy that I bought the boat from said he's had the motor running 3 or 4 times put a new distributor in it has not ran it sense both motors are brand new or somewhat fresh Chevy 350 marine motors that were installed after the order before the guy I bought it from had engine problems and just replace them so supposedly both motors have ran from the says the guy that I bought the boat from and sense of distributors been in these problems have occurred I do not know if it has anything to do with the distributor yet I do not know what it could have to do with at all please help

pS My name is J