Even though this primer includes an extensive review of Pontiac intake manifold basics, it's not just about that. HPP was recently introduced to a new carburetor spacer produced by Wilson Manifolds.

Additionally, changing the effective intake plenum volume and height with a spacer may change the intake manifold's tuning resonance, somewhat analogous to playing with exhaust header tube and ...

In a nutshell, adding a carburetor spacer increases the intake plenum volume by creating a taller neck on the manifold. With the extra volume, the distance between the floor (bottom of the intake ...

which is why racers will play with carb spacers.” Because no two engines are the same, the manufacturers have an extremely challenging design process whenever a new intake manifold is developed.