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Old 01-10-2013, 11:26 AM   #12
supershaft
because I can
 
Joined: Sep 2010
Location: San Francisco Bay area
Oddometer: 8,037
Quote:
Originally Posted by RGregor View Post
Now, obviously BMW recommends that.
And for the specs they provide you have to measure valve lift.
How will you time your cam without proper specs? How will you check the grind?
Or are there other specs around?
Obviously? Where? The 336 bulletin I just read has specs at a 2mm (I was remembering 1mm earlier) lift check point "on the rocker arm". Is 2mm another typo? Why would that be on the valve side of the rocker arm when rocker arm lift ratio will completely change any reading? Our rocker arm design is notorious for having inconsistent lift ratios. Most all manufacturers list cam specs at the crank and not valve lift specs at the crank for that reason. Plus, you can always run different ratio arms on purpose! Valve lift specs vary. The cam lobes don't.

My bulletin has the advanced cam advanced at six degrees too. It is starting to look like they call advancing a cam six degrees three (except in the specs). Between that and listing SOME specs at zero lift I don't think I will be surprised at what I find anymore. Plus the bulletin I just read has the specs listed at (+2) degrees. That's the first time I have ever seen that on a cam card not that I have looked at that many of them. Hopefully we have CAM specs and not wishy washy valve specs. At least the specs for BMW cams have a lift check point!

supershaft screwed with this post 01-10-2013 at 11:48 AM
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