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Old 01-10-2013, 01:05 PM   #13
RGregor
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Joined: Oct 2007
Location: Bavaria
Oddometer: 437
Quote:
Originally Posted by supershaft View Post
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.
The bulletin I have (the german one) also only says "gauge on the rocker", but then "after 2mm valve lift".
So they must mean to measure the valve side.
Thus the bulletin does not contain cam specs. All data are with respect to valve lift.
The rocker ratio ideally is 1.39, but what I'm not sure of is, if there's a constant ration between lifter travel and valve lift throughout the complete movement. So the question is if you simply can calc backwards to get the corresponding numbers for the lifter side if you want to measure there.

Thus the far from perfect method to measure on the valve side may be the better one.
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