Degreeing a cam

The photo above is of my ’66 Commander which I plan to make all-Studebaker. I have put on two new front fenders. To come are new rockers and new rear fenders. I will get at the body work next winter I hope and then do the engine/trans replacement the following summer.

I have been getting a lot of advice from Jim Pepper in the Co-Operator on this engine build. One of the things he recommended was to degree the cam to make sure it wasn’t advanced or retarded from TDC. Now degreeing a cam is something I have read about for years, but I have never really tackled the job believing it to a difficult and tricky process. Well I’m not getting any younger and I’m not sure if I’ll build any more engines (I am thinking of a 185 OHV) so now is the time and a good engine to use to degree a cam. This is a paper degree wheel. One I got from a fellow Studebaker buddy. Certainly not a professional tool! I downloaded degreeing instructions on the internet from a company specializing in degreeing tools – Lunati Power.

First things first. I needed to make up a TDC piston stop. Here I have drilled two holes in a piece of sturdy bar stock to match up with two head bolt holes across the top of the piston.

I then drilled and tapped a hole in about the center spot for the piston stop bolt.

I just used three spacers to give me some flexibility for the piston stop. It won’t actually be used to stop the piston at TDC . I will be used to calculate the exact location of TDC. First step is to get the piston close to TDC just by eyeballing it.

Next I installed the camshaft gear being sure to line up the timing marks. I didn’t have a fully threaded bolt to pull in the gear so I had to use spacers and add a couple every so often as the gear moved inward. I made sure there were a lot of treads engaged before starting the pulling process. I’m sure there is a tool, but not in my tool box.

Next I punched a hole in the degree wheel to fit the crank bolt and then put it on with spacers in front and a large one in back to provide support.

Here you can see the pointer I made out of a piece of coat hanger. I sharpened the end and bent it so that it just touched the card. Once in place I rotated the degree card so that the pointer was at TDC.

To rotate the engine which is on an engine stand I used a ratchet to turn to the right and a pipe wrench on the crank – needs some care here – to turn to the lefty.

I installed the crank key and then wrapped the snout with duct tape. I replaced the tape whenever the pipe wrench broke through, but even so I did do some slight damage to the snout which I sanded off with fine sandpaper. There must be a better way with an engine on an engine stand, but I didn’t get any better ideas. (At this point the pointer is still slightly off the disk.)

Next I moved the piston slightly off TDC and then screwed in the stop bolt to make contact with the top of the piston. I turned the crank to the stop and checked it’s location – here it is at 8 degrees. I then turned the crank in the opposite direction and checked where it stopped on the other side of zero. You need to move the degree card back and forth until the pointer hits the same number of degrees on either side of Zero. This is where I ended up with 8 degrees on either side. I then turned back the piston stop so that the piston was free to move past TDC. Now when I turn the engine to set the pointer to zero on the card the engine will be exactly at TDC

Now that I can set the engine at exactly TDC I need to measure .050 of movement in the lifter for the intake valve of #1 cylinder. I couldn’t squeeze my measuring tool inside the lifter gallery so I had to rig something up. I cut a small length of copper tubing that was just big enough to fit over the dial arm. I pinched the tube about 1/2″ down as a dial arm stop. Now I could mount the dial gauge on the outside of the block and using the copper tube extender I set it all up so the dial and the lifter were in a straight line. With the engine set at TDC on the card I turned the engine until I got .050 on the dial.

I then read were the pointer sat on the card. The first time the reading was 19 degrees which is 2 degrees too high. I went back and rechecked TDC and then tried the lift at .050 thousandths. This time I got 17 degrees which the service manual says is correct for JT engines. To be sure I repeated the process again and the result was again 17 degrees. So I am fairly confident that the cam is in it’s correct position relative to the crank and TDC.

Next I’ll close up the engine front, but leave the pan loose.

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