Degree your Cam

Done during assembly or in the car it still works the same way.

Finding Crankshaft TDC

Get a brake caliper guide pin, its the same thread size/pitch as a spark plug and its pretty stout.  It won't go in far enough to contact the seat where the spark plug seals so don't worry about if it will mess up your head.  Do not insert this into a plug hole unless you know that the intake valve isn't going to open and hit it.  Loosen the lash adjusting screw if you are uncertain.  If you are doing this with the timing chain on, start out at TDC on the compression stoke -the cam dowel is on top, not bottom

Mount your degree wheel to the crankshaft starting when you are at TDC on the timing cover looking at the crank pulley.  Looking at TDC on the wheel, put that to one side where you can easily mount a pointer to the block and bend it over towards the wheel.  File your pointer wire on the tip so its easier to read.  The wheel must be tight and not be able to spin at all.  The crank bolt must be tight enough so it will not loosen when you rotate the motor counter clockwise.  The wheel is part #6120 and it has a few different center hubs with it, if you slice a thin ring from 1/2" copper plumbing tubing is works as a bushing and the degree wheel hub will fit and be centered using a stock cam/crank gear bolt.  You'll need to get a longer bolt to mount the wheel on the crankshaft and a tube spacer so you can tighten the bolt down.

Rotate the motor forward or backward at least 90 crank degrees, pull out number one spark plug and install that caliper pin.  Now rotate in one direction until the motor is locked from turning when the piston hits the pin.  Write down that number you see on the wheel that the pointer is at.  Now reverse the motor until it locks again and note that number on the wheel.  Double check your numbers by repeating what you just did.  Now add up the degrees between you two numbers and divide in half and that number on the wheel is your TDC.  The numbers you get will be somewhere near 25 degrees before and after TDC if you are using the brake caliper pin in the spark plug hole that's the range of movement you will have.  Pull the pin out of the head and move the crank clockwise until your pointer is at that new number you just came up with from finding the middle of that range of degrees.  This should have the crank pulley and notch lined up with the TDC mark on the timing cover or very very close to it.  Now re-bend your pointer wire so its at TDC as showing on your degree wheel.  You now know where TDC is, do not try to rotate the motor by grabbing the wheel and do not bend or otherwise touch the pointer wire.

You need to get a dial indicator that has a way to mount it to the head so you can read the movement of the intake valve.  Put the pin either in front of or behind the valve screw/lifter but not to the side.  If you put it to the side the rocker arm may hit your indicator when the valve is opened.  The indicator you pick may not be the same size that problem might not occur.

If you have a stock cam you know from the factory service manual the valve opening/closing degrees and the duration.  Stock cam duration is 264.  Here's where it gets a little tricky...set your lash to about .003 to start with.  You have to set up the dial indicator with the pin loaded because when that valve is opening the pin is going to drop.  Slowly start rotating the motor until you see the needle on the dial just begin to move and write down the number you see on the wheel in the same format as written in the factory service manual.  After you get the dial indicator set up, rotate the face dial until the needle is at zero. 

Stock Cam Specs:

Intake Valve    Opens   25 BTDC

                      Closes   59 ABDC

Exhaust Valve  Opens   64 BBDC

                       Closes  20 ATDC

Overlap  45 degrees

Intake/Exhaust Duration   264 degrees

That means you need to note the degrees from BTDC ( not ATDC ) when the intake valve is opening then continue on and watch the needle on the indicator until you see that the needle has went back to zero and is a rest.  Note that number on the wheel when that valve is fully closed.  Now that you have the open and close degrees of your motor you need to know the degrees in between these two points.  It may help you to draw a circle then write down the two degree point then connect those points around the circle.  What you are looking for is when you find the degrees between the points its supposed to be, for a stock cam, 264 degrees.  If its not then change the lash by .001 and recheck the open/close degrees points until you get those two points number of degrees between them to be 264. 

Now if you care to check your exhaust valve open/close degrees your wheel shouldn't have to be corrected but its not something you can adjust for.  How they ground it is what you are stuck with.  You can find the centerlines of your cam now using those 4 numbers.  Stock cam intake centerline is 107 ATDC, exhaust centerline is 112 BTDC.

Centerline...

One method of finding the lobe centerline.  You need to know the highest point of lift of your lobe to be able to tell how far off it is from the stock cams intake centerline of 107 degrees After Top Dead Center ( ATDC ).  To get the highest point of lift just rotate the motor until you get what appears to be the highest lift point looking at the dial indicator then re-zero your dial to the needle at this highest lift point.  Very slowly rotate the motor clockwise until the needle has gone one half of one turn on the dial then note that degree number.  Reverse the motor until you get one turn on the dial on the other side of the cam lobe then go back in a clockwise direction one half turn and that gets you .050" on either side of the high point.  The reason you went back (counterclockwise) more than a half turn was so you could come back forward and not have the timing chain so slack because that would give an incorrect degree reading.  Half turn on this dial is .050" or 50 thousands.  Look at the two degrees and find the center of them and that is what your stock cams centerline is set at right now.  Compare that number you get for your centerline to the stock spec of 107 ATDC and that is how for off your cam is.  You need to correct the cam degrees by one half the degrees you are off as the crank turns two times per one turn of the cam. 

How are you going to correct this?

First thing is to remove your dial indicator.  Did you double check all your degree number by repeating this? If you did then remove the dial indicator and rotate the motor forward ( clockwise ) until you are at TDC on the compression stroke.  TDC on the compression stoke is when the crank pulley is a TDC as shown on your pointer on the degree wheel and the dowel pin in the cam gear is at the top. 

This is a 1" flat steel bar, bend a curve near the top and just slide that down in between the timing chain to hold the plunger in the oil pump and it will stop when it rests on top of the crank gear.  Bend down the shelf the cam gear rests on and you can remove the gear, use something to keep the chain from falling.

When they drilled that dowel pin hole in the cam gear they didn't really make it so the dowel was exactly at the top at 12 o'clock when the crank is at TDC they did it so its more like 11:58.  If you look at the way they did that then you can see its better to say that the top is closer to the tip of the gear tooth that is just to the right of the pin location, as looking at the gear from the front, is what it really at the top. 

Look at the 3 pictures below, they put the dowel pin hole in the gear so it lines up with the mounting bolt hole and the tooth bottom in the middle of the tips of two teeth.  If you look at the 3 points: tooth, pin hole and center you will see the one that has all 3 in alignment means that when you look at the gear when installed its the bottom of a tooth that is at 12 o'clock.   

Items needed:

You need a few simple inexpensive items.  I found some of these at a craft store, an office supply or school supply isle of a department store should have some of these.  The degree wheel you can buy or print on paper by finding one on-line.  A  6"- 8" diameter protractor.  A dial indicator with mounting arm.  An old cam gear to be used as a pilot hole for drilling the new dowel pin location. 

You can see the two different protractors overlap and are transparent.  The gears will center on an old camshaft and distributor drive gear.  You need to find a bushing of some type that keeps the two cam gears centered when bolted down so your dowel pin hole will not be off.  You can see that one of these two protractors has one half degree markings too.  You are going to rotate the old gear forward a few teeth, I used 6 teeth. 

Stack all this up and it looks something like this but first make sure your two gears have their dowel holes lined up.  Different brands of gears are made differently.  You can see the difference in the teeth and that one is cut from a steel plate and the other is just cast iron.  The teeth on the gears should be the same and spaced the same.

See small protractor and the larger protractor behind it?  You won't be drilling into a protractor and its easy to see the degrees of correction.  All you need to do now is rotate the top gear forward by one half the crank degrees that you are off then partially drill the hole into the lower new gear.  After you get that hole partially drilled, remove the upper gear and just put the lower gear in your drill press and complete the drilling.  If you are in doubt about the degree numbers you are off and want more adjustment choices, you can move on around the wheel and put in several different dowel pin holes just be sure and write down what each pin is and how it effects the crank degrees for cam timing.  You can get a set of metal number stamps and mark the gear also.  If you want to skip the part where you mount it to a camshaft, you can lay out the degree marks on a sheet of paper all you will need are the ones that go the degrees around one tooth of the gear -you'll only need 10 or so lines.  You can judge the distance of one degree from looking how that is in width along the tooth and stack two gears up and use the old one for your guide but its more precise if you leave them bolted to a camshaft or some other holder.  If the dowel pin hole is off in degrees that's ok just drill another hole but if its off in distance from the center of the gear you won't get it on your cam the dowel won't line up so make sure its all lined up before you start to drill the new hole.