Home › Forum › Ask A Member › 1958 Johnson 10 hp- worthy for resto? › Re: 1958 Johnson 10 hp- worthy for resto?
The ’58 range of Johnsons were amongst the most beautiful ever made.
Yes, OMC motors of that era typically have lower compression than mercs, but it’s not uncommon to have 100-120 in a motor that old.
I would check the gaskets, the reeds and the rings before calling 72 the real compression. If it’s been sitting for some time one or more of those might have issues.
I’d focus on the rings: Let it sit with some Kroil, Kerosene or fogging oil to see if that’ll loosen up rings.
No way to check possible upcoming clutch issues without opening the l/u. You can do it by only taking out the 6 screws holding the lower half of the gearcase on. Do not remove the gearshift pivot pin, just let the lower half drop by 1/2 inch, and you can see the clutch "teeth", with the aid of a dental mirror.