I believe Michigan Wheel says the tip clearance should
be 15% of the diameter of the prop. Check
michiganwheel.com ....There is a lot of data there.

Try Hagerty....They are great! I have had two Chris Craft woodies and my 1956 Rolls-Royce with them, and the service is excellent. They support our hobby in many ways, and their rates are very reasonable.

I have been using the same impeller in my CC-M engine for five seasons and it is still like new. I remove the impeller when I winterize my engine, and coat the impeller with a little glycern. I wonder if the new spare I have carried for three years, may die of old age before old one gives up. Carry ...

The best selection of rubber impellers seem to be
at West Marine or Boat US...

Gentlemen: I have just restored my CC-M engine water pump. It is the gear type with screw down grease cups.
What would be the best grease to use in this pump?