almost_les
Zone Head
Posts: 590
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posted August 30, 2009 01:34 PM
a trick that makes is a bit easier setting up the dial indicator is having the base angled to match the valves. when everything is on the same axis, adjusting the ams to get the right allignment becomes esier. you can adjust one axis without throwing off the other two
  
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dougmeyer
Needs a job
moderated
Posts: 2713
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posted September 02, 2009 11:35 AM
A note to all you ANALytic types. Don't make too much of a deal about keeping the indicator plunger in EXACTLY the same vertical plane as the bucket. It really doesn't matter, just as it doesn't matter if you don't see full lift travel. An angularity mismatch here will effect RATE equivalence of the indicator and the bucket AND the overall travel (lift), but will not affect the lobe center measurement.
Remember, you can pick ANY lift number to use as an opening and closing "index" number. Metric types use 1mm, us old hot rodders use "50 thou". These points are used to eliminate the judgment call of exactly where opening and closing lie, and to provide an apples and oranges comparo between cams and builds. When you are simply trying to accomplish a setting of a specific lobe center, it matters not what the actual lift is, only that you use the same number on the dial indicator at open and close to do the math.
D.
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It's not that I think you're dumb, it's just that so much of what you know isn't true....
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tcchin
Zone Head
Posts: 867
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posted September 02, 2009 11:40 AM
Measuring PTV accurately will require reasonably good axial alignment, right?
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dougmeyer
Needs a job
moderated
Posts: 2713
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posted September 02, 2009 07:09 PM
Reasonably. Error will be the "wrong way", i.e., less room that you see on the dial and the more the angle the worse the error. I'm just sayin' .....if you're just looking at centerlines it's not a big deal.
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It's not that I think you're dumb, it's just that so much of what you know isn't true....
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tcchin
Zone Head
Posts: 867
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posted September 02, 2009 08:36 PM
quote:
I'm just sayin' .....if you're just looking at centerlines it's not a big deal.
Agreed, provided you have symmetrical opening and closing ramps. You know how my friend Murphy likes to spend quiet evenings with me in the garage...
quote:
the more the angle the worse the error
As in x cos(a), where x is the measured PTV distance and a is the angle between axes. (Example: you measure .050" with 30* between axes, and your real PTV is only .043.)
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