Originally Posted by RGregor
I've been told once to refrain myself from cam discussions but at least I'll share the information I have.
The BMW service bulletin that is floating around here in Germany is from July 1980 and it says:
The position of the key slot of the cam is changed by three degrees.
The timing numbers show an advance of six
degrees with respect to the crank.
| Nockenwelle 0° |
| Nockenwelle 3° |
| Einlaß öffnet 32° vOT |
| Einlaß öffnet 38° vOT |
| Einlaß schließt 52° nUT |
| Einlaß schließt 46° nUT |
| Auslaß öffent 52° vUT |
| Auslaß öffnet 58° vUT |
| Auslaß schließt 32° nOT |
| Auslaß schließt 26° nOT |
Are these specs correct?
These are the same numbers shown here:
Anyone ever checked them?
I was at least one of them.
That I hadn't noticed. Like I just mentioned earlier, I have noticed other errors in the 336 bulletins.
Like I have pointed out many times before, I have never timed mine. I am just going by what I have heard and read and seen with other cams as far as saying that cam specs are at the crank but then again I am starting to see all kinds of weird ways to list cam specs out of Germany such as specs with 0 lift compared to most all other cam sources I have seen and read of. I had noticed ambiguity in the wording but not the numbers until now. If I am wrong I won't feel too bad because when most tuners say they have advanced a cam three degrees, they mean at the lift check point with the wheel on the crank. They don't mean it's really 1.5 degrees because we know that the cam spins at half the speed of the crank? Or put another way: Most tuners are mostly talking and concerned with when that intake valve is closing in relation to the crank just like all the other spec numbers are in relation to the crank. Timing the valves IS the whole point! Pj has timed his.