Cam Degreeing

[Wbulk]

I have been degreeing in cams in engines for going on 30 years. Over most of those years the cam grinding accuracy seemed to be pretty good. Occasionally I would run across a cam that had to be adjusted a couple of degrees, but that seemed to be rare. I am in my 60s now and decided to build one more engine. This will be a spare, and I may not ever use it. While degreeing the cam I found it was ground wrong and could not be adjusted. The intake closing was off six degrees. Opening two degrees early and closing four too late. The intake center line was off by two, but the exhaust numbers were right on. So adjusting one way would throw off the others.

This is two of the last three cams I have installed that could not be adjusted. The last one was 5 1/2 degrees off. When I called the major companies tech support the guy tried to tell me that the cams were ground 4 degrees advanced which means, "it's only 2 degrees off." I shot back, yes they are, but the 4 degrees is already built into the cam spec card numbers. He responded, we'll what do you want. Another cam, I responded. Both bad cams were from a big cam company.

So, word to the wise degree your cams when building engines. Check opening and closing at .006 and .050. and the intake center line. When Isky got other companies years ago to agree to compare cams at .050 that did not mean the cams should only be checked at .050. Some companies now only want you to check using the Center Line method. But, I agree with Crane Cams, that this does not tell the whole story. You need to know all the numbers are so you can accurately determine what is going on with your cam.

Both cams were replaced and the replacements were accurate within one degree. Good luck.

[Gaz64]

Wayne,

Good info, and good to hear you do like most I know and check everything.

I don't trust anything either until I know I've measured.

I could see lots getting into trouble if only going by lobe centreline.

[bobcowan]

Like you, I always degree the cam during assembly. Even if I'm using the same cam during a general overhaul. I'v never had one out by more than 1*. But I still do it anyway. And your story is exactly why.