Ok. I went ahead and bought this old timer because as near as I can tell almost everyone thinks they are almost bullet proof. This unit is a nice looking 74 merc 500. Compression is 160, 160, 40, 160. What are the chances the third cylinder is a valve problem more than a cylinder problem??? The unit is in very clean condition and the previous owner swears it ran great when he stored it 8-9 years ago. I know his memory isn't so sharp but I believe this is a highly desireable motor because of its pedigree. I have a rebuild manual and am looking for an opinion or two. I have plenty of mechanical ability and can rebuild almost anything so please be honest, frank and helpful!!!!
also this motor does not have any valves if it's a two stroke, J