How to degree a camshaft

[dbeardslee]

So in my never ending search for accuracy, I started wondering if my timing pointer was mounted correctly. Didn't occur to me until later that when I redid the head, I had the indicators on the cams pointing at the dots and the indicator was pointing directly at 'T', so It's where it's supposed to be. Just before that synapse fired, however, I found this nice little pictorial on camshaft degreeing. The pictorial is for a V8, but the principles are the same, and as some members might find it useful, thought I would pass it along.

[EricHa]

Here are a couple of other sites with info:

webcamshaftsdotcom

oldkawmandotcom (Look under Big Bore Rebuild)

[TADracer]

This is always an interesting subject.

I have been using slotted cam gears for a few years now so having the proper tools and accurately degreeing a cam is a necessary part of my yearly Spring time 'go thru everything' tune up. For my particular combination I find that I like both intake and exhaust cams running at 4 degrees advanced. This has the effect of making the power band come on about 500 RPM earlier but does hurt the top end slightly. Since I do not do a bunch of riding over 100 MPH, this is not a real concern for me. 4 degrees at the crank is only 2 degrees actual at the cams so being accurate and having the right stuff to do this is kind of important.

In order to properly degree your cams you will need a good degree wheel. Motion Pro makes a nice one (the timing plate is useless for this) , a 1" travel dial indicator with a very thin extension, a bracket of some type to mount the dial onto the motor and a piston stop to find an accurate TDC. All this is can be done on the #1 cylinder so everything is on the left hand side of the bike.

Accuracy is important so you must mount the dial indicator onto the motor directly and not with a magnetic base to the frame of the bike. The cushion and give of the motor mounts will give eroneous readings on the dial indicator if it is mounted onto the frame.

First, mount the degree wheel and piston stop to find TDC then remove the piston stop. Exact TDC is required or all your readings will be off.

Mount the dial indicator so the extension is touching the top of the valve bucket or the shim and zero it out. Then find the actual lobe centers by rotating the crank in the proper direction until the dial indicator reads your checking height. I use .040". Read the degree wheel then rotate the crank until the valve opens completely and then closes back to .040" then read the degree wheel again. Subtract the smaller reading from the larger reading, divide by 2 and then add 90 and that should give the lobe centerline in degrees from TDC for that cam. If you have slotted cam gears and plan to adjust then beforehand loosen the bolt that will be hidden in the chain well when at TDC on the degree wheel (since you will not be able to get to this bolt when adjusting the cam degree) then you can adjust the cam by loosening the other cam gear bolt which is now visible and carefully rotating the crank as much as needed then retighten the cam gear bolt. This lets the gear rotate while not moving the camshaft and it is a very small movement. Then do the check again using the same procedure. If you did everything right then your new reading should be your new lobe center (either advanced or retarded). After doing this I usually disrupt the dial indicator then zero it out and check again to make sure I get the same reading. Then do the other cam. Some say you should do the exhaust first then the intake but I do not know why that would matter.

If you adjust your camshafts then it is extremely important you check your piston to valve clearences. With the dial still set up rotate the crank until the cam has the valve completly open then zero the dial indicator. Then use a suitable tool to push the valve in until it touches the piston and take a reading. This is your piston to valve clearence and you should check this at 5degree intervals from 20 degrees BTDC to 20 degrees ATDC because your closest piston to valve event will most likely not be on TDC.

Degreeing your cams will not give you a kick in the pants difference in power but it does give you the ability to adjust each cam independently thereby spreading or narrowing the overlap event or advancing/retarding both or just one cam, etc. Having the ability to degree your cams is just another tuning tool that is handy to have if you want to wring out the best performance for your particular combination. But, if everything on your motor is completely stock, including air cleaner, exhaust and jetting then I would not go through the trouble.

Back before I added my adjustable cam gears I did do an accurate check of the stock setup with 30,000 miles on the clock and the original cam chain. Factory lobe centers for intake and exhaust is 101 degrees. My readings after 30,000 miles were 101 on the intake and 100 on the exhaust which tells me that chain stretch probably does not have a significant impact on cam timing.