Originally Posted by cope
i picked up a 1 inch tall open spacer would it be worth the time to put on my mild 366 that has a performer intake and eddy carb?
It's worth trying, IMHO. Just don't expect big gains, if any.
An open spacer adds to plenum volume as well as allows the engine to draw from both sides of the intake, much like an open-plenum, 360 degree manifold- just not as much so. And even though the open spacers are most often seen on single-plane intakes, they do have their place on dual-plane intakes- usually as a crutch for other mismatched parts.
It will tend to bias the powerband peaks up from where they are now, hopefully not at the cost of too much bottom end. In my experience the open spacer on a dual-plane tends to work better w/a small carb because it allows the F/A mixture to more easily "make the turn" into the runners before hitting the floor. Or with an engine cammed to make it's power above where the dual-plane intake is working at its best.
But that's why you try it- to see how the engine responds. Sometimes, gains turn up that are much more than expected- you can't always say for sure exactly what will happen.
It would be good, testing-wise, to run the car at the track to compare times and trap speeds. But seat-of-the-pants will tell you what you want to know, most likely.