Quadrajet Secondary Air Valve Spring Replacement & Adjustment
1. Remove carburetor from engine and drain all gasoline. Turn carburetor upside down to gain access.
2. Secondary air valve spring (Q2702) is located adjacent to the secondary air valve shaft on the passenger side of the carburetor.
3. The spring tension is supplied by an adjustment shaft that is positioned thru the center of the air valve spring. The adjustment shaft is locked in position by a tiny allen head bolt.
4. Loosen the allen headed adjustment shaft bolt with hex key (Q4902).
5. Note placement of the secondary air valve spring, and shaft (Q2704).
6. Using small flat blade screwdriver twist and remove adjustment shaft and spring.
7. Place new spring (Q2702) in position. Be sure to hook end of spring around air valve shaft pin and slide adjustment shaft (Q2704) thru center of spring, engaging end of spring in slot until adjustment shaft is flush with casting.
8. Using small flat bladed screwdriver turn adjustment shaft clockwise, until the spring hook is just touching/putting tension on the shaft pin. This is called “zero tension”.
9. Turn adjustment shaft ½ a turn clockwise. This adjustment is known as ½ turn tension. Generally the air valve spring is adjusted between ½ to 1 full turn, after approximately 1 ¼ turns the spring life will be greatly shortened do to being over stressed.
10. The less tension on the air valve spring, the faster the secondary air valves will open, The more tension on the spring, the slower the air valve will open. Note: The choke pulloff also works in conjunction with the air valve spring to determine the actual opening rate of the secondary air valves.
11. Once the desired tension is achieved, the adjustment shaft needs to be locked down by tightening the adjustment shaft allen head bolt while at the same time maintaining the spring tension with the flat bladed screwdriver.
12. Test drive car to ensure air valve tension is set correctly. If engine bogs and hesitates at full throttle, increase air valve spring tension.
13. Future adjustments can be made with carburetor installed on engine.