How to Set Valves on a 305 Chevy Engineby Robert Bayly
The Chevrolet 305-cubic inch, small block, V-8 engine was released in 1976 as a result of Chevrolet's search for better fuel economy. The 305 was used in various Buick, Oldsmobile and Pontiac models through 1992. It uses the small bore of the original 265 V-8 and the long stroke of the 350 V-8. The highest stock horsepower attained by the 305 was 230 in the 1990 Camaro. The 305 uses hydraulic lifters with individually adjusted rocker arms. The hydraulic lifter system is a "zero lash" system, meaning there is no clearance between the rocker arm and the valve.
Park the vehicle on a level, paved surface and set the parking brake.
Remove the valve covers with a ratchet and socket. Remove the old gaskets. Clean any stuck-on gasket material from the valve covers and cylinder heads with a putty knife. Wipe the surfaces with a shop rag. Remove the number one spark plug.
Rotate the engine with a ratchet and socket on the large bolt in the center of the crankshaft. Turn the engine in a clockwise direction. Line up the groove in the harmonic balancer with the "0" on the timing marker. Remove the distributor cap by pushing down on the hold-down screws and rotating it 1/4-turn counterclockwise. Lift up the cap. The rotor should be pointing to the number one spark plug wire. The number one spark plug is the first one on the driver's side of the engine. If it isn't, rotate the engine another full turn back to the "0" on the timing marker. The rotor should now be pointing to the number one spark plug wire.
Use the ratchet and socket to loosen the rocker arm nuts on the number one cylinder rocker arms. Loosen them just enough so that there is a gap between the rocker arm and the valve tip. Slowly begin to tighten the first rocker arm while you twirl the push rod back and forth between your thumb and finger. As soon as all the play is taken out of the rocker arm and the push rod stops spinning, tighten the rocker arm nut an additional 3/4-turn. Repeat this procedure for the other rocker arm on the number one cylinder.
Adjust the following rocker arms in the same manner: Intake valves "2, 5, 7" and the exhaust valves "3, 4, 8." Rotate the engine another full turn. The rotor should now be pointing to the number six cylinder. This is the third cylinder from the front on the passenger's side of the engine. Adjust the number six intake and exhaust. Adjust intake valves "3, 4, 8" and exhaust "2, 5, 7."
Coat one side of the valve cover gaskets with gasket sealer and fit the gaskets onto the valve covers. Coat the other side of the gaskets with sealer and install the valve covers. Tighten the bolts with the ratchet and socket.
Items you will need
- Ratchet and socket set
- Gasket sealer
- Valve cover gaskets
- "Chilton's Truck & Van Repair Manual 1979-1986"; Chilton; 1986
- "Haynes Chevrolet and GMC Pick-ups 1988-1991"; John H. Haynes; 1992
- Thinkstock/Comstock/Getty Images