Well, the Prussian blue finally came in. Time to lap the props to the shafts and get these babies installed.
Latex gloves are helpful when working with Prussian blue. A little bit of that stuff goes a loooooong ways, and it can get all over everything in no time. Once there’s a thin, smooth coat across the taper, install the prop and rotate, then carefully remove the prop.
This taper and prop, having just been machined, have very good contact. But a touch of valve grinding compound will make it even better.
There’s a limit to how much lapping you can do. Don’t want the prop bore to get too big!
After cleaning up the grinding compound on both the shaft and in the prop bore, it was time to mark the shaft.
This step tells you where the prop should seat with the key in place. Sometimes a prop can get hung up on the key before it’s fully seated on the taper. If that happens, the nuts will feel like they’re torqued properly, but the prop might be nowhere near seated. Marking with a sharpie helps ensure the prop fully seats. The last step was to remove the prop again and installed the key, then carefully re-install the prop for the last time.
I ordered a 2″ socket online ($5…gotta love ebay) specifically so I could torque the nuts to the 100ft/lbs recommended by the prop shop. Once the torquing was done, I removed the big nut and installed the small nut to the same torque, followed by the big nut as the locknut.
It looks like these props were made for Chris Craft in March 1969.
With the props installed, I can now get serious about installing the engines. Until now, I haven’t had a fixed point indicating where the engines need to go. With the props installed, I can set their position relative to the struts and then go move the engines so the gear output coupler mates up with the new shaft couplers I’ll install. But that’s down the road just a bit.