Servicing The Rochester Quadrajet Carburetor

This thick gasket is one of two in the carburetor kit. Carefully match the gasket to the throttle body and main body. Critical areas must seal properly. A leak at the gasket can spill fuel or create a vacuum loss. Take time comparing gaskets and matching parts. A foam insert, provided in the kit, helps prevent fuel seepage at fuel chamber plugs.

Each passageway must be clear of debris. Brass primary jets are securely in place. Here, the accelerator pump's discharge check ball drops into the passageway. The discharge ball retainer screws into the bore. When installing jets and the retainer, use care not to damage these parts. Use a screwdriver blade that fills the slot. Tighten securely.

Install the new needle seat and gasket. This is brass, a soft, easily distorted metal. Use the correct driver tool or a large blade screwdriver to avoid damaging the seat. If the slightest amount of brass sloughs off during tightening, vacuum or air blow debris from the area and passageways. Tighten securely but do not distort the seat.

The float hinge pin and needle have been installed here. The needle has a tiny spring retainer that must be in place. Note the use of a brass float, always a practical upgrade from the factory's plastic or phenolic resin type. A plastic float bowl insert secures the hinge pin and prevents fuel slosh in the float area.

With the hinge pin seated, gently tip the back of the float arm and lightly press the needle against its seat. Do not use excessive force, or you will damage the new needle's tip. Hold the float up and measure the float height in this manner. Float height is critical, determining the operating fuel level in the bowl.

This is the power piston with primary metering rods in place. Note the position of the retaining spring. This spring is important, keeping the rods in place and tensioned. The piston retainer sleeve is part of the assembly and reused. Protect this sleeve. Install it firmly in the bore after aligning the metering rods with the jets.

Primary metering rods and the float retainer/bowl insert are now in place. Float arms must move freely, clear of the carburetor body. Rods must also move freely without interfering with other parts. Primary rods have machined tapers, factory matched to the jet sizes for your engine-another reason to keep the stock carburetor.

A new accelerator pump assembly may or may not come with springs. If not, remove and install the original springs onto the new accelerator pump. Coat the accelerator pump bore with a light film of motor oil. This will prevent friction damage to the pump seal prior to fuel entering the bowl.

Polished metering rods for secondaries are ready for installation. The air horn is in place and retained with nine screws in this 4MV application. Recheck the screw torque as the gasket settles. Slide metering rods carefully into their bores. Use Loctite 242 on the rod hanger's tiny screw threads. Tighten the screw securely to prevent loosening in service.

Drop the choke link and lever carefully into the cavity. This is easier with the carburetor free to turn on its side. Aligning the lever and keeping it in place during vacuum break installation is tricky. If the lever falls off, fish it out gently with a piece of mechanic's wire. With patience, you will get these parts aligned.

Carburetor tilted on its side, a screwdriver indexes the lever, aligning it with the intermediate choke shaft. Keep the rod on the lever and the lever aligned. With the rod and lever aligned, make sure the rod fits into the choke valve arm. Secure the rod with a new horseshoe clip. Make sure the clip will not come loose in service.

Make sure the link rod is in place as shown. You must hook the link before bringing the vacuum break into position. Install the fast-idle cam and secondary lockout lever before aligning the intermediate shaft with the intermediate choke lever's slot. Move the vacuum break into position. Use Loctite 242 on the retaining screw's threads.