18 hp Johnson - 1961 - Mark on top end of cylinder

[k2sno070]

that makes sense. the paint on my engine does not display any of those symptoms so I think I'm in the clear. I should probably change out the thermostat though while I'm at it. This is a little off topic, but as far as gaskets go... should I replace every gasket on the motor when doing this rebuild? So far I have ordered a new head gasket, intake, and exhaust gasket. Should I replace the power head adapter gasket as well? I haven't gotten that far on the tear down yet, but plan to have it completed by the end of the weekend.

 

[Pappy]

Sure....base gasket definitely as it will rip when you pull the powerhead.
Intake gasket as well. This is the time to replace every fuel hose on the engine as well and not with that clear yellow junk,

 

[k2sno070]

I actually already replaced all of the fuel hoses due to cracking and corrosion on the previous ones, so that's at least one less thing. Once I get apart I'll post a few more pictures. Do you have any idea as to what the bore should be on these engines? I only have an electronic version of the service manual and I'm having difficulty finding the specs.