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How to rebuild a Holley 650 carburetor- Part II- Assembly

Holley Double Pump Carburetor
Holley Double Pump Carburetor

Place the base plate gasket on the base of the main body. Install the base plate and tighten the screws, using thread locker. Then insert accelerator nozzles into the choke tower, tighten the screws with a Philips screwdriver.

Next screw the idle screws on the metering blocks (one on each side of each metering block) until they bottom out; counting the number of turns till the bottom is reached. Remove the idle screws along with their cork O-rings. Spray carb cleaner and compressed air to clean each passage.

Install the main jets in the metering blocks with a screwdriver. Screw the power valve in with a 1-inch wrench, ensuring the power valve O-ring goes in correctly. Place new cork O-rings in the idle screw holes. Screw the idle screw into the holes and back to the original settings.

Remove the accelerator pump face plate with a screwdriver and pull out the diaphragm, spring and seal. Replace with components from the rebuild kit and reinstall the face plate, tightening the screws. Next place the metering block gasket on the block and slide the fuel bowl on, tightening the bowl bolts with a 5/16-inch socket wrench. Reinstall the choke body assembly using the original screws.

Then install the carburetor back onto the vehicle and fasten down with original bolts.The 4150 HP model had no choke tower; the list number was stamped on the side, rear or front of the main body of the carb. Newer models of the 650 Holley last digit was 5.The year built was somewhere between 1955 and 1975. The list number could be found on the right corner of the choke tower.