Originally Posted by JCurry
so do the open spacers not work well on a dual plane manifold?? should i go with a 4 hole spacer for my rpm air gap?
Dual planes are something of a mystery to me I must admit. I would think that either style might help depending on the motor. I never did like having to tune the two halves of my carb like a pair of 2-barrels, so a short (1/2") open spacer would be the first thing I'd try. But I don't see why a 4-hole wouldn't do the same thing theoretically that it does on a single plane, i.e. lengthen the barrel for better flow, etc. I realize that the plenum floor on one side of a dual plane is deeper down than the other. This stuff can drive you nuts. I'd try both! Why not? It's such an easy and generally cheap mod, and it's fun to experiment. 04Silverado seems to have a good hint above with his tapered spacer that has the properties of both open and 4-hole (plus more).
04Silverado, I bet the Vortech or Procharger or whatever that is feeding the carb helped a lot too
Inspector, thanks for that cool test. I'll try that before I try the tapered spacer.