Another stupid lead question

[lightman]

My Son and Grandson are using lead to add weight to the Grandsons Pine Wood Derby car. They place the car on the scale and dribble molten lead into a hole in the car until it is up to weight. After it cools they have noticed a weight loss. Last year it was .5oz, this year its .3 oz. Any ideas? My first thought was that the hot lead was drawing moisture from the wood. The total weight of the car cannot exceed 5 oz so this is a fairly high % of the total weight. They ask me if lead changes weight from being solid to molten and I'm thinking no. Still a curiosity!

[mold maker]

It has to be moisture. Nothing else can change weight.
An alternate method is to put a dollop of epoxy in the hole and add shot to get weight. Doing this on the scale insures accuracy.

[Oklahoma Rebel]

that's what my father and I did as a kid, brings back fun memories

[Epd230]

Add the molten lead to .5 over, then use a knife to remove lead until you are back down to weight.

[Charliemac]

We use to drill holes and insert boolits and seal them off with hot glue.

[Mitch]

yep go with the epoxy glue and the weight will stay right there.

[RogerDat]

If over weight a small drill bit can also be used to remove some of the lead plug. If I recall center line and some forward was the best place for weight. Think solid solder and drilled hole was another way that was popular to achieve that distribution.

[truckerdave397]

We use to drill holes and insert boolits and seal them off with hot glue.

This is what I did but without the glue. Just a tight fit.

[lightman]

Just a follow up on the car. The Grandson won 3rd place!