I am waiting on delivery of the Indy dual plane Dominator flanged manifold. Not finding any good overhead pictures of it, I'm not sure if the divider goes up to the flange or not. I have been advised to run a one inch open spacer under the carb and was wondering if anyone using one has had to mill the divider for better performance?

The divider has a notch cut out to connect the 2 sides. I tried a 4 hole spacer and an open spacer back to back on the dyno.

Not surprisingly, the 4 hole had more under 4,500rpm (10+/-) while the open had more over 4,500rpm (20+/-).

I ended up with a 1/2" wood open spacer. It really dropped the carb temp, too.

Thanks for the reply Dave. It really surprises me how much heat the intake absorbs for not having any crossover. I have been running the 1/2" wood spacers on my 2x4 and it stopped fuel perc in the AFB's. I remember, through the years, seeing many articles about lowering the divider wall on big inch, dual planes to increase power up top. As I recall, it had the effect of making a larger plenum and equalizing access to both sides. I would think an open spacer would basically do the same, but figured that I would ask! Lee.