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Re: [Tigers] Camshafts

To: <tigers@autox.team.net>
Subject: Re: [Tigers] Camshafts
From: "Thomas Witt" <atwittsend@verizon.net>
Date: Sun, 07 Mar 2010 21:26:46 -0800
 Mauro,
If you can't get a part number for the specs you can try other methods to 
get a "general" idea.  My Tiger has a "mystery" cam.  I used a degree wheel 
and a dial indicator to take readings.  Regardless of that, my research 
indicated that cam grinders use different starting points for measurement. 
While the "lift and duration at .050" is common today, older cams likely 
have "advertised" ratings.  And, while one might assume these numbers start 
at "0" lift (just prior to a measurable lift) I often found .006 and other 
standards were used.

Even after you get lift and duration readings it tells you nothing about the 
"ramp" of the cam unless you plot it at a significant number of degree 
points. At best I'd say get a lift and duration at .050 readings (for modern 
comparisons) and then eyeball the cam profile. The broader the ramp is at 
the top the more likely the cam is aggressive for its rated lift and 
duration.  Lastly the lift is tied to the rocker ratio which typically (but 
not always) is 1.5 to 1.  So, a cam with a total valve lift of .450 will 
only read .300 if measured at the lifter.
Tom 
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