To advance or Not

I'll give you the experience I had. I've only installed one cam but I did degree it. It was a very small MP Purple shaft that I lot of guys would say not to worry about degreeing. Something in the machining was off so far that I thought for a while that I was doing something wrong. Found that the key-ways in the double roller timing set were not 4 degrees apart as advertised. I ended up using the closest of the 3 key-ways and had to make an offset key for the timing gear. If I had installed dot to dot, the cam would have been retarded 6 degrees. I decided then, any cam I ever install will be checked although I will have to study up to be able to do it again.