What "Degreeming" a Camshaft Means and Why It Matters

Degreeming a camshaft means measuring exactly where the cam lobes sit relative to the crankshaft, then adjusting the camshaft's position if it has drifted from the manufacturer's specification. The camshaft controls when your engine's intake and exhaust valves open and close. If it rotates even a few degrees out of position, valve timing shifts, and your engine loses power, runs rough, or burns fuel inefficiently.

You degree a camshaft after installation—either when you first bolt it in, or if you suspect it has slipped on its sprocket or chain. The process uses a degree wheel (a marked disc that bolts to the crankshaft), a pointer, and a dial indicator to measure lobe position against crankshaft angle. It is not a task every owner performs, but it is standard practice in engine building and necessary if you have replaced the timing chain, sprocket, or camshaft itself.

Key Takeaways

  • Degreeming requires a degree wheel bolted to the crankshaft, a fixed pointer, and a dial indicator to measure lobe lift as the engine rotates.
  • You measure the intake lobe's opening point (when lift begins) and closing point (when lift ends), then compare those angles to the cam card specification.
  • If the measured angles do not match the spec, you loosen the camshaft sprocket bolts, rotate the cam slightly, and re-measure until it is correct.
  • Proper camshaft timing affects power delivery, fuel economy, and emissions; even a 2-degree error can change engine behavior noticeably.

Tools and Equipment You Will Need

Start with a degree wheel—a circular disc marked in degree increments (usually 0 to 360, with major marks every 10 degrees). The wheel bolts to the crankshaft snout or damper and rotates with the crank. You can buy a wheel kit that includes the wheel, mounting hardware, and a pointer arm that bolts to the block.

You also need a dial indicator (also called a dial gauge) mounted on a magnetic base or indicator stand. The indicator's plunger rests on the camshaft lobe you are measuring. As the lobe rotates under the plunger, the dial shows how much the lobe is lifting the valve. A cam card or specification sheet from the camshaft manufacturer tells you the exact degree numbers where the lobe should open and close.

Additional items: a socket wrench set to rotate the engine by hand, a piston stop tool (to prevent the piston from hitting the valve), and a marker or tape to note reference points. Some builders use a bump box (a small electric motor that turns the engine slowly) to avoid hand-cranking, but hand rotation works fine for most home shops.

Setting Up the Degree Wheel and Pointer

Remove the valve covers and spark plugs. Install the degree wheel on the crankshaft snout or damper—it must rotate freely with the crank and not slip. Bolt the pointer arm to the engine block so the pointer aligns with the degree wheel markings. The pointer should be rigid and positioned so you can read the wheel clearly as it rotates.

Rotate the engine by hand until the number one piston is at top dead center (TDC) on the compression stroke. You can find TDC by removing the number one spark plug hole and inserting a piston stop tool, then rotating the engine until the piston hits the stop. Once the piston is at TDC, align the degree wheel's zero mark (or 0/360 mark) with the pointer. This sets your reference point.

Double-check that the wheel does not slip as you rotate the engine. If it does, tighten the mounting bolts. A slipping wheel will throw off all your measurements.

Measuring the Intake Lobe Opening and Closing Points

Mount the dial indicator so its plunger rests on the intake lobe of the number one cylinder. Set the dial to zero when the lobe is at its lowest point (the plunger is fully extended). Now rotate the engine slowly backward (counterclockwise, against normal rotation) until the lobe just begins to lift the plunger. The dial will show a small amount of lift—typically 0.015 to 0.050 inch, depending on the cam card's definition of "opening."

When you see that initial lift, note the degree wheel reading at the pointer. This is your opening point. Write it down. Continue rotating forward (clockwise, normal direction) past the lobe's peak and down the other side until the lobe releases the plunger and lift drops back to your opening threshold. Note the degree wheel reading again. This is your closing point.

Subtract the opening point from the closing point to find the lobe duration—how many degrees the lobe stays open. Compare this number and the opening/closing points to your cam card. If they match, the intake timing is correct. If they do not, the camshaft needs adjustment.

Adjusting Camshaft Position If Timing Is Off

If your measured points do not match the cam card, the camshaft has rotated out of position. Loosen the camshaft sprocket bolts (do not remove them completely—just loosen them enough to allow the sprocket to rotate on the cam). Rotate the sprocket slightly in the direction needed to shift your opening point toward the spec. A small rotation of the sprocket moves the lobe position by the same number of degrees.

After rotating the sprocket, re-tighten the bolts finger-tight and re-measure the lobe. Repeat this adjust-and-measure cycle until your opening and closing points match the cam card within 1 degree. Once they are correct, torque the sprocket bolts to the engine manufacturer's specification (typically 15 to 25 foot-pounds for most engines, but check your manual).

If you are working with a chain-drive cam, the adjustment process is the same: loosen the sprocket, rotate it slightly, and re-measure. If the cam is belt-drive, you may need to loosen the belt tension and rotate the cam sprocket, then re-tension the belt and re-measure.

Checking the Exhaust Lobe and Overall Timing

Once the intake lobe is dialed in, move the dial indicator to the exhaust lobe and repeat the measurement process. Record the exhaust opening and closing points, then compare them to the cam card. Adjust the camshaft position if needed to bring the exhaust timing into spec as well. If both lobes cannot be brought into spec by rotating the camshaft alone, the problem may be a bent cam, a worn sprocket, or a chain that has stretched—any of which requires replacement.

Some cam cards specify both intake and exhaust timing, and some specify only one. If your card gives both, make sure both lobes are within 1 degree of spec before you consider the job complete. If the card specifies only intake timing (common for street engines), focus on getting the intake lobe correct and use the exhaust measurement as a reference to confirm the cam has not slipped.

Common Mistakes and How to Avoid Them

The most frequent error is not zeroing the dial indicator correctly. The indicator must read zero when the lobe is at its lowest point, not when the plunger is just touching the lobe. If you zero it too early, all your measurements will be off. Take time to find the true low point by rotating the engine slowly and watching the dial settle to its minimum reading.

Another mistake is misreading the degree wheel. The wheel rotates with the crank, and the pointer stays fixed. As you rotate the engine, the wheel moves under the pointer, not the other way around. Mark your opening and closing points clearly and read the wheel carefully—a misread of 5 degrees will send you chasing a problem that does not exist.

Do not assume the camshaft sprocket bolts are tight enough. Even a slightly loose sprocket can slip a degree or two as you rotate the engine, throwing off your measurements. Check bolt tightness before you start and again after you finish.

Frequently Asked Questions

Do I have to degree a camshaft every time I change the timing chain?

Not if you did not move the camshaft. If you replaced only the chain and sprockets and left the cam in place, the timing should not have changed. However, if the old chain was stretched, the cam may have already been out of time. Degreeming after a chain replacement is good insurance, especially if the engine has been running rough or losing power.

What if my cam card does not list degree specifications?

Some aftermarket cams come with only duration and lift numbers, not degree specifications. In that case, contact the cam manufacturer and ask for the degree card. If they cannot provide it, you can use a reference cam (one you know is correct) to establish a baseline, or you can degree the cam to the intake opening point specified in your engine's factory service manual.

Can I degree a camshaft without removing the cylinder head?

Yes. You need access to the camshaft lobes and the ability to rotate the engine, but the head can stay bolted on. You will need to remove the valve cover to see the lobes and mount the dial indicator, but you do not need to pull the head.

How much does camshaft timing affect engine performance?

A 2-degree error can shift power delivery noticeably—the engine may feel sluggish at low RPM or lose top-end power. A 5-degree error usually causes rough idle, poor fuel economy, or difficulty starting. Larger errors can cause valve-to-piston contact or prevent the engine from running at all.

What if I cannot get the cam to dial in within 1 degree?

If the camshaft will not dial in no matter how much you adjust the sprocket, the cam itself may be bent, the sprocket teeth may be worn, or the chain may have stretched unevenly. Remove the camshaft and inspect it for bending. Check the sprocket for worn or broken teeth. If the chain is old and the cam is new, replace the chain as well.