Re: Impeller – key vs pin to shaft

[Don]

I dunno, I would be wary of using a smaller diameter pin in a impeller that is meant for a woodruff key. I’m not sure I am understanding everything you have explained. I would be wary of this situation and would research it more before putting the engine into service.
I think you have said that the replacement short driveshaft has a pin for the impeller instead of the woodruff key, you also say that the diameter of the pin is smaller than the width of the original key. So, that would mean that the impeller fits loosely over the pin and can rock back and forth. Are you using OEM parts? The engine is a 1966 33hp, correct? I am also very concerned about hearing that you altered the gearcase housing in order to fit the new upper seal in place as well. Something does not sound right. Is the gearcase the original one that came with the engine?
I looked in the 1966 parts book, and it shows a roll pin being used for the impeller: 300771 The short driveshaft is: 554314 The impeller number is:
378891-775521 The upper seal number is: 302545-313284
The 15" driveshaft is NLA, but the long driveshaft seems to supercede to an "shaft and key", I suspect the key is the woodruff key you are referring to. So, I am guessing that your original long driveshaft was the later style with the woodruff key, while your standard driveshaft that you found is the original pin style. I’m thinking there should be two different impellers used here depending on whether the key or pin was used, but the parts breakdown doesn’t seem to indicate that.
I looked ahead in the parts book, all the 33hps up to 1970 show the same driveshaft/pin/impeller numbers. BUT, the 1971 40hp, that uses the 33hp style gearcase shows a woodruff key, but the same impeller part numbers. So, to me, something doesn’t add up here (probably me arithmetic skills). In any event, all these engines show the same impeller part number regardless of key or pin, so that makes me think that the diameter of the pin is the same as the width of the key. If not, then the original style impellers had a loose fit on the pins.
Perhaps others with more experience on this model can weigh in.