Home › Forum › Ask A Member › Identifying a Johnson 5.5(?) powerhead › Re: Identifying a Johnson 5.5(?) powerhead
I’m confused, you say the block the ID plug from a 66 Johnson, so I would assume it is from 1966. Or, are you saying someone pried out the original core plug from this block and replaced it with the 66 core plug, but really don’t know why anyone would go through that much trouble. Perhaps the ID core plug fell out into the pan and the marks you see are from someone trying to secure it in place by peening the aluminum from the block over the plug slightly.
In any event, the 64 models used the top mounted recoil, so the intake manifold would have to be changed in order for a 66 6hp powerhead to fit. What color is the intake manifold? In any event, the cylinder head changed a bit on the 6hp, but that might have been switched over as well. The 6hp head has a slightly different cooling passage/thermostat cover and the plugs are installed on an angle.