Holley 4412 or an OEM two barrel Rochester. The Holley 4412 when used on a Chevy manifold may not have an adapter any thicker than ½ inch with thin gaskets.
The Holley cannot be altered. If you have a Rochester that has been modified beyond the specs, you must run our Restricted Funnel Spacer. Spacer is available at Ricks Performance and must be run with thin gaskets and no other spacers. No additional spacers allowed on either type carburetor, or any
alteration of any kind to the manifold.
Specs are as follows:
Holley: Venturi: 1.376 max, Base plate bore: 1.690 max, Booster verticle
demension: .430 min, Booster legs will show all casting part lines, booster leg width: .260 min , booster
outer dimension: .605 min, booster inside dimension: .385 max, Thickness of
throttle blade and shaft: .190 min, holley choke horn must remain.
Rochester: Venturi: 1.376 max, Base plate bore: 1.693 max, Booster verticle
demension: none, Booster legs will show all casting part lines, booster leg
width: .420 min, Booster outer dimension: .584 min, Booster inside dimension:
none, Thickness of throttle blade and shaft: .190 min, Top on Rochester may be
modified, air filter stud may be installed between venturi.