The Dominant front wheel should be set with Positive cant and tow-in. A drift of 2" in 4' is a good starting point. After I do the final test on my Best track the drift ends up being 2" in 3'. That's as fast as the car will go.
Prepping the wheels is critical. A car will only go as fast as the slowest wheel. The bores must be polished with Novus 2 polish and scratch remover. Novus 2 can be purchased on the Internet. Check the Search function and learn how to lube the wheels.
The Nail. I don't care what folks think of me. The only thing I do to the nail is to very carefully remove the 2 casting marks under the head. The casting marks on the shaft are not involved in the race. Again, there is a very shiny Zinc coating on that nail. Turn it in graphite if you want. You will put an invisible coating on it. I do not sand the axle with any grit of paper.
Here's what I'd like to see happen. I'd like someone to say, To all who keep taking 1st place in their races, please tell me how you build your car from the shape you choose to every, every step you do after you choose the shape. Does everything you do make the block go faster? We'll a learn something.
A reminder. This is about Physics. This is about you. It has nothing to do with your relationship with your scout.