You should add some clean protein to your diet, I would say get about 100 grams of clean protein at least with just an upper body workout. When you start seeing results you will want to do some shoulder shrugs, trust me. Then you can up your protein. You shouldn't gain much weight with just an arm routine, if your weight goes way up, drop your calories, if it comes down, raise your calories, everyone is different so a # would be useless.
Bench press is GREAT for triceps, and it works a large muscle group including chest, which is good.
Bench press is GREAT for triceps, and it works a large muscle group including chest, which is good.