I have a CSB 350 stock, one piece rear main seal, Air gap square bore intake, headers, T56 manual trans, Car is a '34 Roadster, Jaguar rear 3,54:1. Tires are 295/50-16.

Planned upgrades for the engine will be Vortec heads modified for higher lift and a new cam of course.

Would like to have a carb that can be used both on the near stock engine of today and later when it is modified.

I've heard that mechanical secondary carburetors are recommended when the car is not too heavy and has a manual trans. Why is that?