Join Date: Apr 2000
Location: Whittier, California
Use a 4 hole spacer for street & mild strip use, gives a better signal to the carb circuits, even with an open plenum.
I make them out of good wood, but the phenolic or plastic work as well, and no fabrication is needed.
Might look on the carb rear, under the fuel bowl, some of them have a vacuum oprt that is same-same as the port you are attempting to use on the intake manifold. Some carbs have them, most don't though, worth a look at least.
Just FYI, Dominator users have a little (actually-big) trick they use for better performance. They relocate the throttle shafts and plates upwards in the carbs, as much as 5/8 inch. Makes the carb have better transition and better signal at the different circuits. Really helps the intermediate idle circuits in the Dominator. Point is, a good 4 hole spacer does the same as this on the non-Dominator carbs, which cannot use the higher throttle shaft/plate mods without a different (never produced) base. Just fuel for thought.