I had a '63 with the 3x2 set up - and used it for many years on that car as well as others - I finally sold the setup a couple of years ago for quite a lot You can change power valves all day, but one fart back thru the carb when you start the car and it will kill them instantly. You need a new 6.5 power valve AND a new pair of gaskets for the float bowl and jet plate - they leak. Also, it has also been recommended above to move the end carbs just off idle - necessary. Another item, make sure that the end carbs do NOT have power valves, as some '62s snuck by with them installed (quality was not job one then). The holes need to be plugged after removing the PV's if there.