There should be no more than 15 psi between all cylinders. Usual compression
is frrom 90-110 psi with 80 psi being the minimum on older engines.


"mwaidley" wrote in message
m...
Is a range from 120 to 150 a normal top cyl to bottom cyl compression
for a murcury force 120? 30 PSI is a huge range. Before i buy a boat
i thought i would check and see if anyone knew if this was normal or
not? Its a bigger range than i am used to seeing.