What a difference a fuel change can make! As for end float-PAWs have a lot-as do quite a few other UK made engines-it comes down to personal preference in the end. Some end float is essential in a plain bearing engine otherwise the engine would lock up as it warmed up and the crankcase expands faster than the crankshaft. How much end float is enough? Realistically about 5-10 thou. Many have a lot more than this-PAWs, DCs ED's and others. Other than being unsightly-it isn't really a problem as of course the thrust vector pulls the shaft forward when the engine is running-so its only an issue when starting-where excessive end float could potentially result in the crankpin contacting the inside face of the backplate (and very likely if someone uses an electric starter!)
If you want to reduce the end float by all means fit a copper washer though personally I'd use bronze or steel. The PAW prop driver is simply a friction fit on the crankshaft taper-so readily removed by simply inserting a thin screwdriver (preferably an 'instrument' type down one side between the case and the rear of the driver and giving it a gentle tap till the driver releases. You want the tapered blade of the screwdriver to act as a wedge-there is no need to try and lever the prop driver off with the screw driver. Needless to say the screwdriver should be a standard slot type-a philips or pozidrive one wont work in this situation!
Fit your washer, and replace prop driver, fitting a prop and tightening the prop up to assist it seating tight again. It would pay to 'face' the washer on both sides by rubbing it on fine W&D paper on a flat surface (piece of glass?) using a bit of oil to remove any burrs from the faces of the washer, lest these mark either the crankcase nose or the back of the prop driver.
www.modelfixings.co.uk do a nice range of stainless steel shim washers which may prove useful for this job (and probably better than soft copper.....)
ChrisM
'ffkiwi'