The only purpose of degreeing your camshaft is to achieve the correct valve opening and closing points for your specific engine. Even when the cam is ground exactly to spec, other factors can throw the phasing between the camshaft and the crankshaft out of line.
Common causes of incorrect phasing
- Cam or crank gears that are mismarked from the factory
- Keyways machined out of position on the gears
- A misindexed keyway in the crankshaft
- On SOHC and DOHC engines: resurfacing the cylinder head or block retards the camshaft
On SOHC engines with rocker arms, valve tip length, rocker geometry and base circle size also affect the lobe separation, and with it every valve event. Correct degreeing is therefore absolutely essential. Read our step-by-step guide to degreeing the cam.
Tools you need
- Degree wheel: Reveals everything about the valve timing. Larger wheels give more accurate readings.
- Dial indicator with a stand: The stand must be fastened securely to the cylinder head. If your indicator has a magnetic base, you can bolt a piece of steel plate to the cam bearings.
- Pointer: A coat hanger or a length of welding wire works fine.
- Piston stop: For pinpointing true top dead center (TDC).
- Cam card: Comes with the camshaft and contains every specification you need.
Before you start
Check that you have completed all the static measurements and clearance checks: valve to valve, valve to piston, retainer to stem seal, cam to head casting, cam to connecting rod, spring seat pressure and clearance to coil bind at full lift. All parts should be clean and lightly oiled.
About the lifters
Always use the correct type of lifter when degreeing. Hydraulic lifters must never be used, as they can bleed down and give false readings.
For pushrod engines, buy a mechanical equivalent of your lifter. Use a pushrod with an oil hole so the indicator tip seats properly.
For OHC engines with hydraulic cam buckets (as in many modern engines), you need to make up a solid lifter that gives 0.1 mm of valve lash on the base circle. The easiest way is to pull the plunger out of a hydraulic lifter and replace it with a turned steel slug.
Remember to refit the real hydraulic lifter afterwards.
Why it matters
Degreeing gives you an accurate starting point for the valve timing. Most turbocharged and highly tuned naturally aspirated engines respond well to small overlap adjustments, but without proper degreeing as a baseline you have nothing to work from. A correctly degreed camshaft speeds up the whole tuning process.
Questions about degreeing your camshaft? Contact Meksta and we will help you out.
Also read about dynamic compression, overlap and cam drive systems.