How to Install a Timing Gear in a 350 Chevy Small Blockby John Stevens J.D.
Chevrolet’s 350 small block engine features two timing gears. Connecting the timing gears is a single chain. The purpose of the gears and the chain is to ensure that the camshaft and the crankshaft rotate in unison. The timing gears are fairly durable, but the teeth on the gears can become worn. More frequently, the chain itself stretches. Fortunately, installing a replacement chain and gears is relatively straightforward.
Removing the Timing Chain Gears
Position a container underneath the drain bolt at the bottom of the radiator. Twist the radiator cap off the top of the radiator, then remove the bolt from the bottom of the radiator with a wrench. Watch the fluid level drop, looking through the cap opening, then tighten the radiator drain bolt once the fluid level has dropped below the upper radiator hose.
Remove the vibration dampener from the tip of the crankshaft with a dampener puller tool. Not all puller tools are the same, so follow the manufacturer’s instructions.
Loosen the clamps that secure the heater hose and the upper radiator hose to the water pump with a screwdriver, then pull both hoses off the pump.
Remove the water pump’s securing bolts with a wrench, then pull the pump off the cylinder block.
Unfasten and remove the bolts that surround the outer edges of the timing chain cover, then pull the cover off the cylinder block to expose the timing chain.
Turn the bolt at the tip of the crankshaft with a wrench until the circular indentation on the face of the upper timing chain gear points straight down and the circular indentation on the face of the bottom timing chain gear points straight up. In other words, the two indentations must point towards each other.
Unfasten and remove the three bolts that secure the upper timing chain gear to the tip of the camshaft, then pull the upper timing chain gear off the camshaft and pull the chain off the bottom gear. Remove the bottom gear from the crankshaft with a gear puller tool.
Installing the Timing Chain Gears
Slide the lower timing gear onto the tip of the crankshaft, then wrap the timing chain around the lower gear.
Wrap the timing chain around the upper timing chain gear, then press the upper gear onto the tip of the camshaft. Note that a metal dowel on the camshaft slides through a hole next to the center of the upper gear.
Tighten the upper timing chain gear’s three securing bolts with a wrench.
Apply gasket sealer to each side of a new timing chain cover gasket, then position the gasket onto the back of the timing chain cover. Position the cover over the timing chain gears and against the cylinder block, then install and tighten the cover’s bolts with a wrench.
Apply gasket sealer to each side of new water pump gaskets. Position each of the two water pump gaskets onto the water pump, then press the pump into place against the cylinder block. Install and tighten the pump’s bolts with a wrench.
Position the vibration dampener onto the tip of the crankshaft, then tighten the dampener’s single bolt into the crankshaft.
Connect the heater hose and the upper radiator hose to the water pump and tighten the clamp on each hose with a screwdriver.
Pour the drained radiator fluid back into the radiator.
Items you will need
- Vibration dampener puller
- Gear puller
- Gasket sealer
- Timing chain cover gasket
- Water pump gaskets
- “How to Rebuild Your Small-Block Chevy”; David Vizard; 1991
- "Motor's Auto Repair Manual"; Ralph Ritchen; 1968
- Hemera Technologies/AbleStock.com/Getty Images