Auto Racing: carb spacer, stock racing, fuel mix

Question
I'm putting together a 4 cylinder engine for a stock racing class with a 2 barrel carb. The intake has an open plenum. should I use a carb spacer(can be 1.250 inches) that has an open plenum like the intake or use a spacer with 2 holes like the carb.I was thinking of using the one with the 2 holes to create some kind of velocity??? what do you think?

Answer
This all depends on how deep the plenum is in the manifold. Raising the carb is going to move the torque band up in rpm. Depending on how the manifold distribution is designed, you could use either spacer. The idea is to lessen the curve the air/fuel mix needs to make to get to the cylinders. A tight curve causes the fuel to drop out of the mixture whereas a gentle radius keeps the mix together.