Newbe question........
 

I have a glow engine question. I'm a new RC pilot learning on electric but aquiring gear at a rapid rate. Are the factory prop washers and nuts a must? I just bought a bucket full of glow engines and several of them are missing washers and nuts. 21 engines in the bucket, 18 salvagable, 6 running so far. Do I need to buy factory nuts and washers?

If they are four strokes, factory prop nuts are definitely recommended, if two strokes it doesn't matter much.

Some manufacturers parts are interchangeable - or at leas they used to be. For example, Magnum was a Chinese knockoff of OS and the parts were interchangeable. And Tower engines were often knock offs of Super Tigre. So don't throw away those broken engines, their parts might be able to be used elsewhere.

Kinda depends on the engine. You want a thick washer that has the hole the exact size of the prop shaft, and has the hole exactly centered. Both primarily for keeping out-of-balance vibration from happening. For most, a good quality nut of any kind will work - something you can tighten down well. Some engines, primarily larger four strokes, had a special double compression nut arrangement, to better reduce the chance (especially if it kicked back) of the nut/washer/prop from spinning off the shaft. Some had nuts that fit into a recess in the washer. Original equipment is the best, but I'd guess that many have substituted hardware store items, although the risk may be a bit higher. Extremely rare to have a prop come loose in normal running. It almost always happens during startup due to the electric starter, kickback, or fuel lock when flooded.