Re: 1976 Johnson 35HP carbon buildup

[Don]

Be sure to check the rubber cooling deflectors in the block as well. Unfortunately, these engines are prone to overheating, especially with the water pick ups right in front of the gearcase where they are easily plugged with bags/seaweed. I’m assuming you have the gearcase off as well to do a water pump job. I wouldn’t worry about the different combustion chamber appearances too much if the engine was running/idling OK before the overheat problem.