View Single Post
Old 01-07-2013, 12:58 PM   #21
supershaft
because I can
 
Joined: Sep 2010
Location: San Francisco Bay area
Oddometer: 8,399
Quote:
Originally Posted by RGregor View Post
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:
http://bmwmotorcycletech.info/cams.htm

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.

supershaft screwed with this post 01-07-2013 at 01:18 PM
supershaft is online now   Reply With Quote