Re: carb and outdrive ratio
Well, you probably have a model 160 engine, since the 165 model didn't come out till 76, the 160 used a One drive with a 1.68:1 ratio, the 1.65 ratio didn't start till 76 with the 165 engine.
The III drives were used on the V8 engines, like the 327, 350, 427, etc. between 68 and 72.
Don, Just so you know, I had a 1972' Wellcraft Airslot 18.5ft that had a 165hp/250cu in Mercruiser (Type one drive) all original. The horsepower was listed in bold letters on a plate on the motor. This is the one I bought with a siezed engine, that although it looked pristine, I still had to rebuild it. As I recall, it had a large plate over the manifold where the 2bbl carb sat, that i believe you could remove, & put a small 4bbl on, as long as you found a close match, & adapted the linkage. (I never went that far with it) There was an aluminum automotive 4bbl aftermarket manifold available for these inline chevy 6's way back when, they're rare as hen's teeth, and I don't know if they're marine (suitable, matchable, or if it's exactly the same as the Mercruiser used?) but, I believe I read somewhere they were good for 180hp on the 250"/6cyl.
I was the 2nd owner of this boat, I bought it from a young woman who owned a Piano store, and drove, and raced a Porsche 928, she bought the boat new for her dad in 1972! He stopped using it, because it wouldn't start, and it sat for a number of years. She was divorced, and I was also heading that way, I tried to hook up with her, but I was actually not in her class, so it didn't work.
