mercury 59ci blocks

[fs5]

I've done a bit of searching,and found that a stock 59 ci 60hp pumps 120psi compression.i've seen a few guys post on here that a stock merc 40 pumps around 135 psi.merc list a different part number between the two.
has anyone cc'd a 40 or 60 block.

[Nason]

I've got a 2004 59ci and it has 120 psi

[HGipson]

Man that's just what my compression tester said anyway. For all I know the guy mighta shot some oil in the cylinder before I got there that'll make it read higher than why it actually is. I checked it at WOT w/electric start and had the kill switch pulled so it wouldn't start. All three holes showed 135 but again, coulda been error in test or oil added to raise compression for me since he knew I was coming to buy it. Haven't checked it since I got it back together from Hydrotec yet but it fired right up so I ain't mad yet! Got it mounted on boat gonna try her out tomorrow

[MWhite]

Man that's just what my compression tester said anyway. For all I know the guy mighta shot some oil in the cylinder before I got there that'll make it read higher than why it actually is. I checked it at WOT w/electric start and had the kill switch pulled so it wouldn't start. All three holes showed 135 but again, coulda been error in test or oil added to raise compression for me since he knew I was coming to buy it. Haven't checked it since I got it back together from Hydrotec yet but it fired right up so I ain't mad yet! Got it mounted on boat gonna try her out tomorrow

u had to replace a piston didnt u so he probably did that or your tester is off. all my motors show 120 to 123, he probably poured some 90w down them. lol

[HGipson]

u had to replace a piston didnt u so he probably did that or your tester is off. all my motors show 120 to 123, he probably poured some 90w down them. lol

Haha yeah I had to replace the top piston. I meant before I bought it I took my compression tester and that's what it read. I figure that ole boy prolly out some in it. Didn't really care how high it was just wanted to make sure there wasn't 5lb or more difference between any of the three. That guy had motors and stuff laying all around so I figure he knows how to play ball! Lol. Shoulda took that little snap on camera my neighbor has stuck it in there to see what I had but oh well Jon at Hydrotec fixed me right back up so hopefully I don't have to worry about it anymore! But there ain't no telling when I checked the compression tester at the shop before I left it showed to be almost right on the money but the other gauge coulda been jacked up too for all I know! I was so happy to get a mercury again I didn't really care!

[omcstratos]

Merc 40............................118-119 psi

Mercury 50 20" shaft..........125

Two I can remember recently, both bone stock minus the LWP on the 40

[fs5]

thanks for your replies