When I used lead weights, and I don't anymore, I'd put a screw through the cowl, into the weight, to keep it in place. If you don't, the fuel will eventually dissolve the glue and release the weight.

Thanks for the reminder Villa.

Jack

Edit - I have a 6.5 pound trainer (SPAD Debonair), powered by a TT GP-42 and it's a joy to fly.