The plastic spinner back plates prevent a good seat of the prop and nut in my mind. Like you, I like the colors so I use a combo aluminum back plate with plastic nose. Great Planes makes the ones, I use. You find out right away with a four stroke that the plastic back plates will just not do. If you try to tighten it, it mashes out under the pressure needed to hold a prob on in a back fire.

Downunder is a tad off in his recomended torque. A garden varity hardware store screw of 1/4 in diameter is recomended at 9 Ft/Lbs. A grade 8 whick is closer to the screw makeup on a crake shaft is 14ft/lbs. 5/16" screws are twice that. My grig, I'm guessing is around 75 lbs or so. Figure I have an effective pull of about 4" on the 6" cressent so I'm able to pull down around 25ft lbs all out. I probably don't squeze near that hard pulling a prop nut tight, Maybe a bit to much, but I'll tell you this, I've never stripped out a nut tightening it. I've broke of a number of bolts in my time by over tightening them. This is steel on steel. Glow plugs are a different story where you have a very fine thread in cast alluminum with a steel screw.

Thread damage comes from poorly fit threads. Hardware store nuts are thread formed for the most part and 60% thread are all that is needed. A proper propeller nut is machined and has a fuller thread, as does the crank. No wiggle wobble while the thread is loose. You take a hardware store screw and nut and they rattle around some times. If you want or need a jam nut setup, get a four stroke nut set for a few bucks and rest assured that you have a good setup.

Don