I have been told that an Open plane (One big opening) gives higher Upper torque, and a 4 hole spacer gives better lower end torque.
If I go with this 4 hole version Mr. Gasket 3406 Mr. Gasket Carburetor Spacers | Summit Racing
(Mr Gasket 3406)
I wonder if the Carb butterfly's will have enough clearance?
Anyone know?
DavidK
Use an open spacer on a dual plane intake and a 4 hole on a single plane in most cases. Of course different engines want different things. If your engine "wants" a larger plenum then an open spacer may increase performance.