I have tried for over three years to get my 4150 to idle. It would always go past the idle slot and would rev up and down or shut off. What I did today was to take off the lower section with the butterflys off of the carb, and drill the holes on the primary butterflys a little bigger. Wow, what a difference! It now sounds like a million bucks and no more pumping the gas at stop lights to keep it running. It was hard at the track too when I was trying to keep the rpms down.
