How to Set the Timing on a 1986 Chevrolet K5 Blazer

Part of the maintenance tune-up that you perform regularly on your 1986 K5 Blazer should include checking and resetting the ignition timing. When parts in the engine wear, the timing can change slightly over time and resetting the ignition timing will restore the lost performance caused by the wear. This procedure only take a few minutes and is well worth the effort from the home mechanic. A timing light is required for this adjustment and is available at most large auto-parts stores.

Tools Used: Timing light, Service manual, Shop rag, Parts cleaner spray, 9/16-inch distributor wrench

Set Timing

Clean off the timing marks, located on a metal tab on the front of the engine below the water pump, by spraying away the dirt and grease with parts cleaner sparay and wiping dry with a shop rag.

Start the engine and allow it to run until the engine temperature gauge reads in the normal range. On this truck, that is between 165 and 180 degrees Fahrenheit.

Attach the timing light power cables to the positive (red) and negative (black) battery cable ends. Clip the inductive pickup lead from the timing light to the number one spark plug wire. The number one wire on the Chevrolet V-8 engine is the front plug wire on the driver side. Disconnect the four-wire connector located at the base of the distributor by lift the locking tab and pulling the two halves of the connector apart.

Loosen the distributor hold down bolt located on the U-shaped hold down bracket at the base of the distributor, using a 9/16-inch distributor wrench. Start the engine. Aim the timing light at the timing marks and pull the trigger. Turn the distributor to align the mark on the crankshaft balancer, located below the timing tab, with the 8 degrees before-top-dead-center (BTDC) mark stamped on the timing tab. Tighten the hold down bolt securely.

Turn off the engine. Plug the four-wire connector back together. Remove the timing light and test-drive.

Tips & Warnings

Wear safety glasses and work gloves when working around a running engine to prevent serious injuries.