Step 1

Read the warranty before installing the carb. The installation of this unit means that you have agreed to all terms of the warranty.



Remove the air cleaner assembly. Inspect all hoses, diaphragms, and heat riser tubes. Replace all that are bad, loose, swollen, or cracked.

Step 3

Make a rough drawing or a diagram of the carburetor, showing where all of the hoses and wires go. Mark each of the hoses and wires (such as A, B, C, etc.) and indicate each one on your drawing. Compare your drawing to the hose routing diagram under the hood or in the service manual for your vehicle.

If everything does not match, get professional help. Sometimes the book is wrong, sometimes the routing diagram under the hood is wrong, and sometimes a previous mechanic has connected something up wrong. This needs to be carefully checked.

Step 4

Disconnect the following parts as necessary: Choke heat tube, fuel line, vacuum hoses, P.C.V. hose, transmission kickdown linkage, throttle linkage, throttle return spring, and electrical wires and plugs. Retain all hose clamps, linkage clips, plastic grommets, etc.

Use special “flare-nut” wrenches to remove the fuel line, or you may damage the fuel line.

Step 5

Undo the hold-down bolts or nuts and remove the carburetor and the flange gasket. Compare the new or rebuilt carburetor and make sure that it matches exactly the one that you are removing. If there are variations, call the factory or the dealer you bought it from and ask about the differences. You may have bought the wrong unit, or it may be a service replacement unit. If the unit is the wrong one, do not install it. If you install the wrong unit, you may not return it for credit or refund later on. It is fairly common on older vehicles for the incorrect carburetor to be on the vehicle, so be careful.

Compare the base gasket with the one that came off of the vehicle, there are often variations. The carb rebuilder usually includes the most commonly used gasket, but not always the correct one. If the correct base gasket is not included with the carburetor, you may buy it at the vehicle dealership or at an auto parts store. Put a cloth into the intake manifold opening at this time to prevent dirt or chips from entering the engine.

Clean off the flange surface so that the new gasket can seal properly. Keep exposed ends of lines free of dirt. If required, transer over to the new carb any studs, solenoids, brackets, dashpots, hoses, wires, etc. as needed.

Step 6

Remove the cloth from the mainfold, ensuring that dirt doesn’t enter the manifold. Install the base gasket, and shim if required. It goes on dry (no glue or sealant). Be careful how you put it on. Many gaskets will only fit correctly one way. Set the carburetor in place, but do not tighten it down yet. First check the carb for binding by working the throttle linkage fully open and closed again. This is to make certain that the unit was not damaged in shipping. If the unit has an automatic choke (most have) the throttle will only close as far as the fast idle setting. This is ok. Inspect all vaccum and fuel hoses for cracks.

Replace all marginal hoses. Connect the linkage, hoses, & wires. If everyting looks ok, then proceed to tighten the car onto the manifold. Recommended torque for most carbs is 7 to 10 ft/lbs. (Note: 15 ft/lbs will warp most carbs – be careful). Cap off all small pipes on the carb that don’t have a hose attached.

Put a threaded plug in the rear of the carb if necessary because your vehicle doesn’t have power brakes, or if the power brake hose connects to the manifold (certain domestic carbs only). Use a 1″ wrench to hold the fuel inlet securely when tightening the fuel line to a Rochester carb.

Step 7


You must ensure that no dirt can enter the unit via the fuel line. Be careful of fire! It is better to fill the float bowl with gas before starting the engine. Some types of accelerator pumps may be damaged if pumped when there is no gas in the carb.


As soon as the engine starts, check for fuel leaks. If any are found, shut off the engine and repair immediately. If no leaks, check the fast idle speed and adjust to specifications. After the idle speed is set follow the manufacturers directions for adjusting idle mixture via the lean drop method. If unknown, turn the idle mixture rich (out) a little to obtain best running at 50 RPM higher than the normal idle speed, and then slowly turn each mixture screw in equally until you obtain a 25 RPM drop for each screw (a 50 RPM drop if your carb has only one mixture screw). Remember: set speed first & mixture last.