Trying to get the tungsten putty off my fingers after pushing the stuff into three holes I drilled across the rear third of Mr. Boy’s pinewood racer while he watched. He’s too little to hold the big drill, but he helped with the putty, which is intended to add weight to the 2-ounce body of the car, almost another full ounce. Weigh-in day is next Saturday when the cars are approved/disapproved by the Cub Scout race committee and impounded until the race the next day.
After the plastic wheels and steel axles are on, the whole thing should weigh a bit over four ounces. Five ounces is the max allowed. I don’t think we’re going to come to close to that this year. Bought the tungsten in place of lead, which is toxic, as we all now know, from this pinewood derby outfitter.
It’s important to get as close to five ounces as you can because the only "motor" these things have is gravity. But the outfitters offer all sort of tips, such as bending up one of the front axles so the car runs on three, instead of four wheels, offering less drag and friction. Rules we have from the race committee don’t mention that. Once we get it all painted in Mr. B’s preferred colors of red, gold and white, I’ll post a picture of it.
UPDATE Should add that, at the weigh-in, the officials said I should use the available hot glue gun and lead weights to bring the total weight up to almost 5 ounces. I got it to 4.92. I didn’t buy enough tungsten putty. Two ounces of it would have been better. I was still able, even with the lead, to distrubute the weight on the rear 60 percent of the car.
THE TEXAS SCRIBBLER 
Was wondering if the tungsten putty stays put once it’s place in the car? Did yo cover it with anything? Would appreciate the information. Thanks.
Sure. Once we pressed the putty into the holes–we had to roll it between our fingers into thin, cigar shapes to get it in the holes–we covered the holes with ordinary wall spackle, available at any hardware store. Smooth it off with fingers, let it dry and sand it down even with the wood. Though I must say that after using the putty, we discovered some glue-on lead weights which are sold in sheets. You snap off what you want and use an electric glue gun to stick the weights on the bottom of the car with hot glue. The putty and holes make the car prettier (all the weight is hidden) but the lead weights are easier and quicker to apply. Plus being on the bottom, they aren’t visible when the car’s on the track. You really have to get as close to the maximum-allowed weight as possible for good performance. Good luck!