A 4160 is a 600 holley not a 390. and this could very well be your problem.Thats why it is still loading up the plugs at idle.It is also a Vacum sedondary So yes it does have the transfer tube.The main Jets in that carb are at least a size 66 and you can't go much lower then a 60 with out having to go to a smaller carb.
God doesn't like ugly.
