1968 Mercury 500 4 cylinder

[duffer1960]

I bought a 1968 Mercury 50 hp outboard. It has the inline 4 cylinder engine. I got it for a winter restoration project, and will rebuild the powerhead. 2 of the cylinders have low compression. Does anyone know what the factory compression should be for this model? Cylinder #1 has the highest compression at 100 psi. #4 cylinder has nearly 0. I thank anyone for their info.

 

[turtles11756]

Re: 1968 Mercury 500 4 cylinder

i have three 50hp late 60's merc motors the best one has even compression in the low to mid 130psi range. these have never been rebuilt .factory new i would guess at about 140psi 145 ?

 

[duffer1960]

Re: 1968 Mercury 500 4 cylinder

thank you for the info.