Serowbot wrote on 08/19/08 at 10:00:06:Ace hardware also has a nylon washer that is 66% of the stock spacer. That's what I used,... hope it is gas tolerant.
Most nylon grades have good gasoline resistance. You're probably OK.
Among the plastics, Delrin, would be my choice material. Good chemical resistance and ideal as a washer. I haven't taken a look at the spacer so I am not sure what material it is made of.
Other choices would include olefins, which have a very high resistance to liquid gasoline. Glass-reinforced polypropylene would give good physical properties for a washer. High density polyethylene is commonly used for blow molded gasoline tanks, but the physical properties may not be ideal for a washer.
Brass and some other metals have good corrosion resistance to gas and should be fine but I'd stick with a plastic washer if possible. There are a number of properties that engineers design for and unless you know them all you might be making a trade-off in long term longevity.
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