Robert,
My 70 is the same way. My drums were original and un cut when I did my brakes, the knock out plug was never removed. Being I did not want to remove it I adjusted the brakes by expanding the star wheel adjuster a little at a time. Each time I would replace the drum until it fit just snug with a slight drag on it when spun - with the tire off. You have to get a good feel for it.
Don't make it too tight as it can heat things up and liquify your brake fluid.
Hope this helps.
Rich
------------------
70 SS - L34
Member # 442
www.chevelles.com/showroom/richr1
http://www.my70ss.com
My 70 is the same way. My drums were original and un cut when I did my brakes, the knock out plug was never removed. Being I did not want to remove it I adjusted the brakes by expanding the star wheel adjuster a little at a time. Each time I would replace the drum until it fit just snug with a slight drag on it when spun - with the tire off. You have to get a good feel for it.
Don't make it too tight as it can heat things up and liquify your brake fluid.
Hope this helps.
Rich
------------------
70 SS - L34
Member # 442
www.chevelles.com/showroom/richr1
http://www.my70ss.com