What is meant by degreeing a cam?

Question

In the hot rodding world, "degreeing the cam" is an often used term when installing an aftermarket camshaft. What does the term mean, what does it do for you, why should you do it, and what are the procedures/tools used to perform it?

Answer 1

Degreeing a cam is process for installing a camshaft and then verifying it's proper alignment with respect to the crank shaft.

If a camshaft is being replaces due to damage or malfunction with another OEM camshaft generally the degreeing process is not performed. When the camshaft is installed a set of timing marks is lined up and this lines up the camshaft. The following is just one possible setup, every engine has a different alignment procedure.

When installing an aftermarket camshaft for performance reasons the manufacturer specifies the correct alignment for that camshaft. The alignment of the camshaft is specified as crankshaft degrees when the cylinder number one intake valve reaches 0.050 inches of lift. For example 8 degrees before top dead center (BTDC).

First install the camshaft and alight the marks available. Next rotate the engine to the top dead center of the number one cylinder. Next install the degree wheel, an indicator of some kind (a bent wire in this case) and something to turn the engine with (a crank handle in this case).

Next adjust the engine to make sure it is exactly at top dead center. There are lots of ways and tool available to do this. I like a dial indicator. Adjust the degree wheel so that the top dead center of the engine, degree wheel and wire indicator all match.

Now place a dial indicator on the number one intake lifter and rotate the engine backwards until 0.050 inches of lift is achieved.

Once the lift is achieved the read the cam wheel.

If this matches what the manufacturer specified then your all done. If it does not then the camshaft orientation need adjusted. This is usually done with a special gear or key way. For example, for this small block a special gear is available that takes inserts that offset the relationship between the camshaft key and the gear.

This procedure is long and tedious with the need for attention to detail. I have generally glossed over the procedure. This was not meant as a comprehensive guide, it was meant more as an introduction to people not familiar with the procedure.

Answer 2

You utilize a "degree wheel" and a piece of metal on the front of the motor. The engine is rotated until the true top dead center marks line up. Usually done when a cam shaft or chain is changed. Fairly common with older vehicles since the indicated marks on the balancer can slip with age resulting in the vehicle getting out of valve train time.