How to degree a camshaft and the benifits on Honda Cars

Technical
Engines work best when the right things happen at the right time. For instance, when ignition spark happens too late, you might embarrass yourself on the dyno; when it happens too soon, you might end up with a scenic view of the inner workings of your block. The relationship between an engine's cams and its crank is no different. The rise and fall of the pistons has to synch up with the opening and closing of the valves. This is even more important to pay attention to once aftermarket cams, adjustable cam gears or other mismatched components, each with their own tolerances, are factored in, as well as once an engine's deck or cylinder head have been resurfaced. Even the slightest tolerance change or amount of material removed will alter the distance between the cams and the crank, which, in turn, will alter their relationship with one another and disturb cam timing. All of this makes it even more important to properly degree your cams.

         Cam degreeing-or "zeroing in" cam timing-is the only way to ensure that your cams are performing optimally and that your piston-to-valve clearances are what you think they are. It's also the only way to ensure that your valves open up all the way at precisely the right time. It's a process that should be performed whenever cams are swapped or an engine's been rebuilt-before visiting the dyno. You'll need adjustable cam gears to do it, as well as a degree wheel, a dial indicator, and some basic hand tools.

        But don't assume that cam degreeing has anything to do with dialing in your adjustable cam gears to some predetermined setting. Your cam gear manufacturer has no idea how much your block's been surfaced, how many times your head's been milled, or who manufactured your cams. Neither does the kid on the internet whose, incidentally, got "the same setup" and assures you that a couple of degrees of advance on your intake cam is exactly what you need. To be sure, cam degreeing is more than simply the twist of a couple of adjustable cam gears based off of where the cam gear manufacturer says "zero" is. Degreeing cams ensures that the cams are in their correct position-for your engine-nobody else's. The guesswork's eliminated.

   Before degreeing cams, though, you've got to understand some cam fundamentals to help better see why all of this needs to be done. A good grasp on the four-stroke process won't hurt either. 

THE FOUR-STROKE PROCESS — The four-stroke cycle gets its name from its four piston stages: intake, compression, power, and exhaust. For every 720 degrees that the crank spins, each of the engine's pistons travels up and down twice. Meanwhile, the valves, carefully controlled by the cams, introduce air and fuel into the cylinders and let exhaust gases out. In the real world, the precise beginning and end of each cycle is pretty foggy because of cam profiles and all sorts of complicated physical and chemical constraints. Instead of 180-degree increments, an engine's valves typically remain open far longer in order to introduce enough air and release enough gas. Proper valve timing is critical to how well the four-stroke process works, and proper valve timing begins with cam degreeing.

CAMSHAFT DEFINITIONS
When discussing camshafts, enthusiasts often get confused with the terminology used to describe the various parts of the camshaft. This diagram and these definitions should help most people better understand camshafts and their related terminology.

Ramp
The textbook definition of ramp is the section of the cam from the base circle to where the valve physically begins to open, or finishes closing. It is also commonly referred to as a clearance ramp; or in other words, the part of the cam lobe where the camshaft will close up the initial tappet clearance (lash) and the tappet/follower will make initial contact (on the opening side) or end its contact with the camshaft (on the closing side). Skunk2 defines ramp as the portion of the profile from the base circle to the point of maximum valve acceleration. Skunk2's Fast Ramp Technology helps the valve go from zero to maximum acceleration as quickly as possible and still maintain superior valvetrain stability.

Flank
This is defined as the end of the ramp section to the point where the valve reaches maximum velocity. We frequently hear people talk about "aggressive ramps" when they are actually trying to describe the flank and how quickly the valve is opening. It is important to find the balance between opening the valve too quickly and not opening the valve quick enough. If the valve is not opened quick enough, "area under the lift curve," the airflow is not optimized. If the valve is opened too quickly the camshaft may run off the tappet, and it will become difficult to slow the valve down enough as it goes over the nose.

Nose
Nose is defined as the section between the maximum velocity on the opening side and maximum velocity on the closed side, or rather the section of the cam where the valve spring forces are keeping the valvetrain from separating from the cam surface. Controlling valve accelerations over the nose is critical to preventing valve float and high-rpm valvetrain stability. Skunk2 Amax Technology allows the company to design the flank and nose section of the cam to maximize area under the curve and still maintain valvetrain stability.

Tool You Will Need

Dial indicators
degree wheel
sockets

1 Visually set the Number One piston to TDC (top dead center), remove the crank pulley, and fasten the degree wheel to the crank with its TDC mark pointing up. The process is easiest with the engine on a stand but can also be done with it under the hood.

2 Cut off a six-inch piece of welding rod or a metal coat hanger, bend it into a "J" shape, and sharpen its long end to a point. Slide a bolt through its "J" and fasten it to the engine, somewhere below its cam gears, allowing the rod's sharpened end to point toward the degree wheel's TDC mark. Position the rod close to the wheel, without touching.

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3 When degreeing cams, never rely on the engine's pulley, block, or timing belt/chain cover markings to locate TDC. Variables like block height and piston dwell often make such methods inaccurate. Instead, use the piston-stop method to determine precisely when the piston's reached its absolute highest point and the middle of its dwell. Rotate the crank so its Number One piston is near the bottom of its bore and thread a piston-stop into its spark plug hole. You can fabricate your own piston-stop out of a spark plug or anything that threads into the spark plug hole and hits the piston just before TDC. Next, rotate the crank in its normal direction of rotation-counterclockwise for most older four-cylinder Honda engines, clockwise for most newer ones-until the piston contacts the piston stop, and note the wheel's degree value corresponding with the pointer. Rotate the engine the opposite direction until the piston contacts the piston-stop again and record that value. TDC is located exactly halfway between those two values.

4 Without moving the crank or degree wheel, reposition the pointer to line up with the degree wheel's halfway point you just recorded. Now, remove the piston-stop and rotate the engine in its normal direction of rotation, this time aligning its TDC mark with the pointer. Be sure it's dead-on, and don't disturb it. You've now accurately located TDC and, chances are, it's not where your timing cover and crank pulley said it should be.
5 Position your dial indicator's tip on one of the Number One piston's intake valve retainers. Don't position its tip on the rocker arm as the rocker ratio will distort the results. For an accurate reading, be sure that the dial indicator's needle is parallel to the valve. You may need to fabricate some sort of base that bolts the dial indicator to the cylinder head to position it appropriately. Close the valve lash all the way, and ensure that the valve is closed completely by checking that the rocker pad is positioned on the camshaft's base circle, not its lobe.
6 Rotate the crank in its normal operating direction. Observe the dial indicator's reading as its respective valve opens. Keep rotating the crank until the pointer lines up with your cam's specified peak lift degree value, also known as its intake or exhaust center line, depending on which cam or lobe it's referring to. This information can be found in some service manuals for OEM cams and from the manufacturer for aftermarket ones. If you overshoot your mark while rotating the crank, continue for another full rotation until everything lines up. Never rotate the engine in the opposite direction since a tensioner will only align its cams and crank appropriately when spinning forward.

7 With the degree wheel positioned at your cam's peak lift degree value, loosen your adjustable cam gear bolts and rock the cam back and forth until the dial indicator shows its valve is at full lift. You'll know it's at full lift when the gauge displays its numerically smallest reading. Ensure that the crank hasn't moved, tighten the adjustable cam gear bolts, and rotate the engine two complete revolutions, this time monitoring when the dial indicator once again displays peak lift. Observe the degree wheel to ensure that it's once again at your cam's advertised center line. If it isn't, start over.

8 Repeat the process for the opposing exhaust cam lobe, using the appropriate exhaust peak lift specifications.

9 If you made any sort of adjustments, you'll want to re-mark your adjustable cam gears to reflect their new "zero" reference points. For example, if you retarded your intake camshaft one degree to coincide with its peak lift, then "minus one" degree is your new "zero."