[Dick Boneske]

Originally Posted by Kenth

Dick, .046" idle tubes? I´m sure its a typo and you ment .036".

JMHO

The OP noted his engine will have a hydraulic roller cam and 459 cubic inches. He's aiming for 500 hp, which means the cam will be fairly radical.

I've restored Tri-Powers on many Pontiac engines. Very few owners retain the factory cams, which changes the requirements for the idle circuit, jetting, and power valve. In this case, the cubic inches will grow from 389 to 459, which also changes the carburetor calibration.

The numbers I posted for idle tubes, idle bypass restrictors, throttle base hole size are not typos. These numbers are based on experience, not conjecture.