Reply To: compression 57 3 hp Johnson

[Don]

Don’t be afraid to “deglaze” the cylinder walls using some fine emery cloth, this might help the rings seal and bring up the compression….These engines don’t have much compression, so 60 PSI isn’t that far out of the expected range. These engines have such small combustion chambers, compression readings tend to be inaccurate. You have the head off, no signs of scuffing/scoring, no signs of stuck rings/scuffed pistons with the exhaust cover off….Be sure the head/block surfaces are flat before installing the new head gasket…