Originally Posted by SkyPilot
You got that right, A TB spacer was beneficial on an older carbureted car because it gave the air and fuel more time to mix before reaching the cylinder. Since on our cars (and every care these days) fuel is introduced right at the cylinder they serve no purpose.
Makes a nifty paperweight tho!
A phenolic one will help keep heat out of the intake manifold since, most cars have coolant lines running through the throttle body. It also, indirectly makes the plenum larger.