Anyone try the two oval hole carb spacer on the 4 hole plenum intake manifolds?

[427LX]

If you wanted to increase plenum area a bit by taking a maybe 1.5 inch 4 hole spacer and removing the separation between the primary and secondary bores about a inch down and radius the remaining wall.

[Joe-JDC]

What manifold are you referring the question to?  Slotting the manifold first and making it a divided plenum instead of four holes usually works quite well at increasing the volume and helping with turning the airflow into the runners without adding a spacer.  In dyno testing, we found a divider spacer can help to a point, but a divider with 1" or 2" super sucker type of spacer was better.  Joe-JDC 

[427LX]

This intake.....

Right now I'm running matching 4 hole 1.5 inch tall spacers. Had thought of milling the primary/secondary web out about 1 inch down in another pair of spacers to give a better flow of primary/secondary at WOT.