Primary rods and jets for 455 Buick

[trusty67]

I have an early style qjet (73 Buick 7544540) on a 455 engine with a few minor upgrades (headers, aluminum intake, mild cam). It is a 4 speed car and part throttle cruising is hesitating and bucking. So I am assuming it is running lean at part throttle. It idles decent and WOT works fine,  The primary rods are “45B” so they are 0.045” cruise diameter with a .026” power tip. I see on this earlier model you can not adjust the APT from the top. Any suggestions for a good size primary rod for this application? Thanks

[Kenth]

The application number is stamped on the widest part of carb, between the air valves and throttle blade axles. Not sure about your number.
If it is a 7043240 i would keep the 45B rods and use #75 main jets.
Also i would use .036"-.037" idle tubes and at least .055" idle down channels.
HTH

[trusty67]

Ok thank you I will look into that

[Cliff Ruggles]

Even better remove the APT screw in the baseplate and install one of our external APT screws. 

Then you can raise the power piston up/down and have full control of part throttle A/F......Cliff