Im confused again... Lets start over talking about advance /retard and how it effects the crank and / or my calc... since the other problem seems to be solved.

This is what my calc says:

Remember to use crankshaft degrees, and not camshaft degrees. If you have a value in camshaft degrees, double it to get the right crankshaft degrees (eg. 4 becomes 8, or -3 becomes -6).

I would assume that most numbers given would be crankshaft degrees... since really when you think of a measurement that is camshaft degrees the only one should be the LSA (Lobe Seperation Angle). So the above statement serves really as a reminder if you for some reason have camshaft degrees. IS the reminder causing the confustion?

Now think of a cam and a crank and how they turn together.

Here is an illustration i just made in photoshop:

The small circle is the crank and the larger is the cam. The arrow shows turning direction.

We know that for every one turn / revolution the cam makes, the crank makes 2. In other words, the cam rotates at half of the engine speed.

Now imagine the cam reversing 10 degrees in one direction.

If the cam reverses direction by 10 degrees, then the crank would also reverse direction, but by 20 degrees.

Do you see the math now?

If for every 1 (cam) you get 2(crank) then x*2

Using the 10 degrees above that we reversed the cam (-10) we now have -10*2 which equals -20.

This of course applies to how you get crankshaft degrees from camshaft degrees NOT how you actually advance the cam... that could be where the confusion enlies.

My question is now this... when say for example the crane cam for our I6's give the spec for retard at -2 degrees, is this spec at the cam or at the crank? Thats the real question! I would assume the spec is at the cam since its usually relative to the intake lobe at TDC right? THAT is why the reminder is there! You have to take those cam degrees and double them so we can get crank degrees.

So are you now saying that the advance / retard figure that is entered by the person using the calc should be in cam degrees instead of crank degrees?? If so, we cant do that because having the cams retard / advance in crank degrees play an integral role in how DCR is calculated. .. well i guess i could change the math to do the multipication for the user ... are you thinking i should do that???