A new timing chain, gear or belt set only performs as designed if the camshaft is correctly timed to the crankshaft. One tooth off can cost power, cause rough running, trigger cam/crank correlation codes — or, on an interference engine, lead to valve and piston contact.
Before You Start
- Confirm the timing set matches the engine. Sprocket tooth counts, chain type and key positions can differ between engine versions.
- Have the correct timing procedure for the engine; mark locations and alignment methods vary.
- Inspect the cam and crank keyways, the sprocket locating dowels and the threads for the cam bolts.
Aligning the Marks
- Set the crankshaft to top dead center as the procedure specifies.
- Install the sprockets and chain or belt with the timing marks aligned exactly as shown for that engine.
- Remember that on some engines aligned marks place cylinder #1 on the overlap stroke, not compression. Account for this before installing a distributor or timing the ignition.
- Install the tensioner and guides, then release the tensioner.
Verify Before Closing Up
- Rotate the crankshaft by hand two full revolutions in the normal direction and confirm the marks line up again. Never rotate an interference engine against resistance.
- Check camshaft end play where applicable, and confirm any thrust plate or retaining hardware is installed.
- Torque sprocket bolts to specification and use any locking tabs, thread locker or new bolts the procedure calls for.
- Install oil slingers or crank spacers in the correct orientation.
- Install a new front crank seal while the cover is off.
How Machining Can Affect Cam Timing
On overhead-cam engines, resurfacing the cylinder head or decking the block reduces the distance between the crankshaft and camshaft. That changes the chain or belt geometry and can shift cam timing and tensioner position, typically in the retarded direction. A light cleanup cut usually stays within tolerance, but excessive milling can cause timing errors, tensioner problems or correlation codes. When significant material has been removed, check cam timing against specification and use a corrected-thickness head gasket or adjustable cam gear where available.
On cam-in-block engines, decking does not change cam timing, but it can affect pushrod length and valvetrain geometry.
Evergreen Timing Components
Evergreen offers timing chain and timing belt components and complete timing kits identified by engine application. Use the Evergreen eCatalog to find the right kit for your engine. Browse Evergreen timing components.
