I can confirm on my 1960 40hp that these are hex head screws that require 3/16″ allen key.
And after much struggle with the allen wrench i was able to loosen 8 of these 13 screws. They hold the powerhead to the adapter plate. The service manual states “Remove the powerhead to adapter plate retaining screws, including those partially hidden by the motor support and shift handle, then lift of the complete powerhead assembly”
I can’t access the ‘partially hidden’ screws… any suggestions on how to get to these?
