New motor/1050 dominator won't idle

If you run the idle screw all the way in you will completely expose the transfer slots and start pulling fuel from the main circuit. No more than .020" of the transfer slot should be exposed. As stated earlier, check for vacuum leaks, float levels, fuel pressure and if you have adjustable air bleeds, make sure the restrictions are appropriate to rule out any problems in those areas. If you're running a 45 power valve you've probably got a pretty snotty cam I would imagine! Lol! Personally, I would plug the power valves and up-jet accordingly. Depending on your idle vacuum, the power valves could be dumping extra fuel into the mix as well. The next step would be to crack open the secondary throttle plates. The adjustment should be on the underside of the carb (it is on a 4150 anyway). Again, don't expose any more than .020 of the secondary transfer slots. Once all that is done and you still can't get a decent idle you can drill holes in the primary throttle blades. Obviously, you want to make sure your idle screw and throttle plate adjustments are correct then start small and work your way up in drill size until you achieve acceptable idle quality. Be careful not to go too far all at once because once the holes are drilled you can't go back. Not easily anyway!