Degree'ing in the cam - HOW?

[bighairyralph]

I think that says it all. I need a solid explanation of how to degree the cam in. I friend did it with me once, but as it typical, it went in one ear and out the other. At least that's how it seems four years later A step by step would sure be nice and a good contribution to the board. Particularly if it included HOW to actually change the timing of the cam and what difference retarding and advancing it makes. I know it's a time consuming pain to type all that stuff out, but it sure will help alot of people. Thanks!

[grizld1]

You need a degree wheel, a pointer to line up with the degree wheel, a dial indicator, a holder for the dial indicator (I use a Flexbar holder--love it!) a TDC indicator, and specs for your cam telling when, in degrees, the valves should open to a specified amount of lift (usually .050", but this varies) with how much valve lash (usually none, but this also varies). Neither of these conventions applies to the stock cam. Adjust cam chain tension. Line up the rotor on the stator TDC mark, remove the stator and rotor nut, and mount the degree wheel to the crankshaft with the "O" roughly aligned with the rotor mark.Install a pointer--a piece of coathanger wire ground to a fine point with a loop for mounting in the other end--on your bolt of choice so the point lines up with the "0" mark of the wheel. For the next step caution's needed. Pull both plugs and insert the TDC indicator in the left side hole. Let the plunger contact the piston top and note its position on the height scale on the plunger, and locate another mark on the scale about 9 mm. up from it (it can be any significant distance, really, but I've found 9 mm to be a fairly interference-free spot where the plunger doesn't tend to get locked up). Now rotate the crank CCW, till the plunger drops to the chose line. Relieve pressure on the plunger as you turn--did I mention it can lock up? Record the degrees shown.

Now pull the plunger up (don't unthread the TDC indicator) while you turn the engine CCW till you get fairly close to (not at) the same number of degrees BTDC as your first degree reading ATDC. Relieving plunger pressure as your go (did I mention it can lock up?), find the spot where the piston's risen to the same line as you used for the drop reading. Record the number of degrees shown. Before you forget, remove the TDC indicator (did I mention it can lock up?) Subtract one number from the other and divide by two--that's the number of degrees by which your initial setup is off. Loosen the crank nut, realign the degree wheel with the pointer, and tighten up. Repeat the above to confirm. You now know where true TDC is.

Rotate till the left side valves are all the way closed. Now reset valves to the appropriate lash. Most folks just do the number on an intake valve of the #1 cylinder (left, on our bikes), but hey, that dial indicator's a new toy, so go crazy! If you have a Web or Shell cam, that valve lash would be 0. Fasten your indicator mount in a handy spot, position the indicator plunger on the valve stem or retainer and zero it, and rotate gently till you have the specified lift (.050" for Web and Shell). Read the degree wheel. If it corresponds to the specs, you're good. If not, you know how early/late you're opening.

It's late-- I can't recall tooth count on 447 and earlier cam sprockets and the part of my poor ole brain that does numbers is already asleep, so you can do the math--but bearing in mind that engine rotation is CCW and the cam sprocket's geared 1:1 to the crank sprocket, you can determine how far to move the sprocket to adjust the valve opening. Score the camshaft and the cam sprocket to show a position that'll give you the degrees of correction needed and take it to a shop that can press the sprocket off and reinstall it to the marks--or take it to a shop with experience with your numbers in hand and tell 'em the thing turns CCW and the valves need to open x degrees sooner/later. When you get it back, do it again--even experienced tuners have been known to go the wrong way.

Correction--camshaft of course turns at half the speed of the crank, and on the 447 engine there are 36 teeth on the camshaft, so that 1 tooth=5 degrees of crank rotation. And another correction (thanks, pj!): 10 degrees of cam rotation=20 degrees of crank rotation.

[grizld1]

Oops--caught a typo. For those who read earlier, see the edit! Cam sprocket's of course geared 1:1 to the crank.

Oops again--it's of course 2:1, which is of course how a single ignition cam gets 2 cylinders to fire 360 apart.

[crazypj22]

Hi Grizld1,
Its a lot easier to just do this stuff than to write about it (at least in my opinion ;D)
36 t cam sprocket is 10 degrees between teeth and 20 degrees crank rotation?
damn, now you've got me wondering if thats right
PJ

[grizld1]

You're right--toldja I was in one of those states where the numbers were goin' numb! Think I've done achieved what you're workin' on, pj. Well what the hay--one more edit!

[bighairyralph]

It's always harder to write down a procedure then it is to simply do it. I spend a good part of the day answering tech questions on pistolsmithing. That's why I really appreciate you taking the time to sit and type (and edit) it all in. This way a bunch more people will be able to do a job that is pretty important. Now I just need to make a degree wheel (to cheap to buy one - they want real money for those things!)

[grizld1]

I use two of 'em, Ralph--a metal large-diameter wheel from Domiracer for use with a pointer and a transparent plastic protractor from Staples that I pressure-fit to the center hole of the crank to verify timing marks--they're usually off a degree or two, and easy to reindex with a dab of paint. Domiracer also makes a TDC plunger.Their stuff is surprisingly cheap and nice quality. Holeshot also offers decent stuff for a reasonable buck. I didn't spec procedure for the stock cam because it's given in the manuals, and Bob Bertaut has the procedure and specs with photos on his site, along with specs on the impact of valve lash on valve timing for the stockers--a thou' makes a difference! Folks with stock engines who want just a little more giddyup may be surprised just how much difference it makes to index the stock mill.

[650motorcyclescom]

Here is the link:
www.650motorcycles.com/isky.html

[islanddave]

Hello All,

Does the web cam grind 59-a that is available from Mikes have to be degreed in or is it just set up like a stock cam would be?

Thanks Dave

[islanddave]

Hello All,

Maybe I should have read the post before asking questions............ well a little humility develops charcter, but must I endure so much humility in my life??


Thanks Dave

[grizld1]

It depends on whether you want to optimize performance. Your bike will run without it; some folks break in the new cam sprocket and cam chain first and then degree the cam, since those components have an impact. See Webcam's site--they recommend degreeing for their products. The stock setup isn't put together with a whole lot of precision. It's common for timing marks, for example, to be as much as 2 degrees off; and bear in mind (thanks again, pj!) that any error in cam sprocket alignment is doubled at the crank.

And thanks for those specs, 650motorcyclescom--that article's terrific, and your generosity in taking the time to write it and share it is deeply valued.

[islanddave]

You make an excellent point and observation regarding how some folks prefer to break in a new cam and chain first before degreeing.............thanks for that, never would have thought of that one! I think I shall wait to degree the cam.......of course wiring has to be done first...then the engine needs to be assembled, but before that the cylinders need to be bored.....wow I am a long way off...........one day at a time!

Thanks

Dave

[bighairyralph]

Nothings cheaper than this;

www.tavia.com/free_degree_wheel.html

I think I'll still make one from aluminum on the mill

[jack]

Unless the cam sprocket is being reproduced,which I thinks the old sprocket is just being pressed back on after cam regrinding,the sprockets already have their break-in period,so now would be the time to dial-in the cam cuz with a new chain,it could take miles to stretch the chain,so why not reap the benefits at the time of re-assembly.........Jack

[crazypj22]

Couple of pics. You'll be building engine on bench so you may as well set up posative stop on piston to set degree wheel. I got lucky and was less than half degree out so I didnt mo ve it around just for pic
;Dhttp://img520.imageshack.us/my.php?image=posativestop1fp.jpg
The piston is from XV750, machined slightly to fit XS combustion chamber (800cc)
Heres the degree wheel, flash was a bit bright
img520.imageshack.us/my.php?image=crankrotateccw6wf.jpg
img520.imageshack.us/my.php?image=crankrotatecw1dw.jpg
I ran out of time today so didnt get very far with engine, but, garage is looking a bit better and I have some more shelves to load up with 'stuff'
I'll take some more pics when I get head back on, Its been milled about 0.050" so I'm interested how far that puts the cam timing out (stock cam)
PJ