430" Engine Carburetor Note

On 7028240 carburetors after Change Letter "A" (see CARBURETOR IDENTIFICATION ), new primary nozzles were used and specified pump setting is 13/32" with pump rod in outer hole. DO NOT reposition pump rod or change setting on these carburetors.

1. 3) After changing pump rod setting to 9/32", adjust Vent Valve to new setting of 3/8" (See ADJUSTMENTS ).
2. 4) In severe cases where complaint not corrected by above procedure, raise the fuel level by changing Float Level setting to 3/8" (see ADJUSTMENT ).
   CAUTION: Do not increase fuel level beyond this 3/8" float level setting which could cause main nozzles to supply fuel at idle speed and make it impossible to secure a smooth idle adjustment.

• 1968 CADILLAC COLD ENGINE STUMBLE OR STALL ON ACCELERATION CORRECTION:  A possible correction for a car that will stumble or even stall when accelerating with choke on may be to lengthen carburetor choke rod to 2 rod diameters past gauging notch or index mark. This adjusts choke 2 notches richer.
• 1968 PONTIAC 400" V8 ENGINES IRREGULAR EXHAUST NOISE AND ROUGH IDLE ON 2-SPEED AUTOMATIC TRANSMISSIONS CORRECTION (Auto. Trans. Cars Before 10/10/67):  Production change listed below for these engines will eliminate this complaint on later cars. Rework vacuum system and change idle speed setting as follows:

1. Remove yellow-strip hose from carburetor port to TVS and vacuum hose from TVS to retard port on distributor vacuum unit and discard these hoses (do not remove steel hose fittings from TVS). Cap these 2 fittings using No. 9781338 Caps or connect tubes with short piece of discarded hose to exclude foreign particles from TVS. Cap the open port on carburetor with same type cap but DO NOT cap port on distributor vacuum unit. Check and adjust ignition timing.
2. Set idle speed to revised increased RPM: Solenoid Active Idle Speed in Drive  - 650 RPM (was 600 RPM).

• 1968 PONTIAC 400" V8 ENGINES SPARK RETARD & IDLE SPEED PRODUCTION CHANGE (Engines with Auto-Trans. Only):  At approximately 10/10/67 following changes were made to improve idle and reduce exhaust noise:
  1. Vacuum hoses from carburetor ports below throttle valves to TVS and from TVS to retard side of distributor vacuum unit were eliminated (this eliminated timing retard action at idle).
  2. Engine idle speed was increased as follows: Solenoid Active Idle Speed in Drive  - 650 RPM (was 600 RPM).
• "C.C.S." & "A.I.R." ENGINES NOTE:  These engines have special exhaust emission controls as follows: All Engine  - Specially calibrated distributors and carburetors, closed positive crankcase ventilation system, and related control units. C.C.S. Engines  - Have "thermo air cleaner" with vacuum powered, thermostatically controlled, air cleaner air intake for control of carburetor air temperature. A.I.R. Engines  - Have an air pump for air injection in engine at exhaust valve ports.