Hello again. I appreciate the help I got with my last question. I was able to get a rebuild kit for my Holley carb on my 401 C.I. engine on my 1966 F-850. Now I need some more help. The engine would only run if you left it mostly choked, if you un choke it even at operating temp it will back fire thru the carb when trying to accelerate. I was told it was probably a blown power valve which is why I needed the rebuild kit. I rebuilt the carb, replaced the power valve yet still have the same problem. What would cause this to happen? Any suggestions? Thanks for any help.