1973-1982 Corvette Emission System Install

Your Mission, if you choose to accept it, is to install that missing emission system on your Corvette. Back in the Sixties to Early Eighties, one of the first things that you did was to remove the horsepower robbing smog system. After you removed it, you threw it away because you would never need it. Were we ever wrong!

Today, not only do show cars have to have the smog system if they were originally equipped that way, it is also needed to get the car registered or to renew your license plate in some cities and states. An operating smog system is very important today.

Until now, most smog systems were very expensive and hard to locate but thanks to Zip Corvette Parts, 8067 Fast Lane, Mechanicsville, VA 23111, (800) 962-9632, help is but a phone call away. They have almost all of the parts needed to completely re-install that missing emission system. We installed a complete smog system on our 73 Corvette in one afternoon and it was fairly easy to do. So let’s get our tools and get started. After completely reading this article, it will self-destruct in 5 seconds. Pooff!! 1973-1982 Corvette Emission System Install:

Step 1

01: This is a complete emission system for our 73 Corvette: Pump, diverter valve, injector tubes, check valves, EGR valve, diverter elbow, gaskets, vacuum hoses, smog hose set, PCV valve and clamps. You will also need a shop manual and assembly manual which are also available from Zip.

Step 2

02: Start by installing the smog pump mounting bracket to the intake and water pump.

Step 3

03: The vacuum advance solenoid should now be installed. If you do not have one, contact Zip. They should be able to help you.

Step 4

04: Pre-lube all of the air injector mount holes in the exhaust manifold with anti-seize compound and install the right and left injector tubes.

Step 5

05: Install the check valves to the air injector tubes. Also, coat the threads with anti-seize compound.

Step 6

06: The new air pumps look identical to the original pumps. The only difference is that the mounting holes have metric threads. This means that you will have to modify the diverter elbow to fit the new pump. The mounting holes will have to be enlarged. To do this, clamp the diverter elbow to a block of wood with a “C” clamp. Place a 19/64” drill bit in a slow turning drill and carefully enlarge both holes. Now remove the 19/64” bit and replace it with a 5/16” drill bit. Enlarge both holes again to this size. Now the new holes will accept the larger shaft metric bolt.

Step 7

07: The only other slight modification you will have to make is to the pump housing. The new diverter valve is slightly larger than the original and it will rub against the pump housing when it is installed. To correct his slight problem, take a file and file down the ridge where the diverter valve touches the pump. Fit the valve before final assembly to insure a good secure fit.

Step 8

08: Secure the diverter valve to the pump. Do not forget to use a gasket between the elbow and the pump and the elbow and diverter valve.

Step 9

09: The air pump adjusting bracket should now be installed. Next install the pump to the mounting bracket and adjusting bracket. Do not tighten any of the adjusting bolts.

Step 10

10: The air pump pulley can now be installed. If your Corvette is an L48 or L82, you will need this spacer. If it is an LS4, you will not.

Step 11

11: Install the EGR valve and gasket. Make sure you have a clean mounting surface before you install the gasket and valve.

Step 12

12: With the air pump loose, install all of the smog hoses. Adjust the pump to its farthest point then cut and mount the hoses and clamps. This way the hoses will not be too short and limit the adjusting of the pump. Also install all of the vacuum hoses and new PCV valve.

Install the V-belt and adjust its tension as follows: The amount of deflection should be as follows:

10” ½”
14” 7/8”
20” 1 ¼”


When the tension is set, torque the pivot and adjusting bolts to 25-30 ft. lbs. Caution: Before starting the engine after installing your new air pump, make sure that the pump pulley and drive belt do not interfere with or rub against any hoses or brackets in the engine compartment.

Step 13

13: Here is our 73 L48 ready for installation with its new smog system. MISSION ACCOMPLISHED

Emission Impossible: 1968-1982 Smog System Installation

Source: Zip Corvette Parts
8067 Fast Lane | Mechanicsville, VA 23111 | (800) 962-9632

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