This is what I found in the Johnson service manual.

It is very important to tighten slowly and evenly. Start in the middle and go in an increasingly expanding circle.

Of course none of these take into account the copper gaskets. . . 🙄

Pay attention to your fastener sizes. There are a pezillion tables available online that can give you required torque values for any given fastener size and type. Also pay attention to the material that the fastener is made out of, it makes a slight difference in how much torque they can handle. Google "torque specifications for small fasteners" and see the tonnage of info that is available. What motor you have doesn’t really matter, its the size and type of fasteners that are important.

I could tell you what the torque is, but in my tiny little mind, its better to help somebody learn how to do it for themselves eh

Hope this helps

best,
PM T2

Going from a "challenged" memory, I think the recommended torque is 15-18lbs. But, those heads will require continuous torqueing after several runs before you get a really good seating. The test is to look at the spark plugs after a good run and see if there is any water droplets on them. Original head gaskets were all copper with a, for lack of a better word, ring that sealed the edge of the cylinder. The new gaskets Randy had made have a copper ring with the rest of the gasket being paper. They work fine. The PO’s had a similar design in later years. If there is going to be any leakage, you’d want it to go to the outside, not into the clinder bore. If you’ve sanded your heads on a flat block you should get a good fit. So torque, run, torque, run and inspect, then repeat if necessary.

George makes a good point about re-torquing. When I was building car engines, the standard practice was to re-torque cylinder heads after the initial run was completed on a fresh engine, and you did it HOT. I was taught to break the bolts loose one at a time, and re-torque to specified value immediately before moving onto the next bolt i the sequence. The end result was that I built many street performance engines and never had a single cylinder head gasket failure in any of them. I’ve never rebuild an antique outboard that had cylinder heads on it (although I’m in the process of working on a Kobunn), but I have done several cwassic OMC’s, and I always retorqued those heads too, I guess it just became habit.

Best,
PM T2