Custom Holley 850 – 1050 1-3/4 bore Racing Base Plate

This is a custom Holley mechanical secondary base plate with 1-3/4 throttle bore that will flow a ton. Includes the 30cc pump arms. This was originally a 4777-2 650 base plate that was machined to the bigger bore and set up for a giant cam, was used in a late model oval track car. A lot of detailed machining work done. The primary transfer slots were reworked. The primary idle discharge ports (under the throttle blades) were not modified. Has both a manifold vacuum advance port (front vacuum tube) and ported vacuum advance above the throttle blade (if using a primary metering block with an advance provision). The secondary side was converted to four corner idle. The secondary idle discharge channels were terminated just ahead of the former inlets. The secondary idle transfer slots were eliminated and instead replaced by new idle discharge ports, though which a secondary metering block will trim the fuel to the secondary corners. And extra idle air is piped in for a big cam (the car was using dual 4.5 power valves) by channels on the driver side of the carb (see the photo with the yellow circle to see how it was done); it feeds both the primary and secondary side. Primary shaft was welded, and there is no play, shafts are solid and work great, and a nice opening rate.

• Brand: Holley
• Type: Throttle Base Plate
• OE/OEM Part Number: 4781, 4777-2
• Manufacturer Part Number: 4781, 4777-2
• Material: Alloy
• Vintage Part: Yes
• Country of Origin: United States
• Performance Part: Yes