[Amc-list] Cam Specs

[southconsulting@xxxxxxxxxxxxxx]

AMC used a standard for measurement that was common to the automotive industry
during that time of rating the camshaft measurements at .004" tappet rise. 
The .425" lift spec was used for the the duration of 1966-1979 production. 
Maybe later, but I have not been able to uncover documentation to support it.
 A major difference in timing, however, occured in 1971.  Seems they were
having trouble getting the engines to pass new fed emissions requirements, so
the changed up the events and lift rate of the camshaft.  The pre-71 and early
71 camshafts were 196 degrees at .050" (266 degrees advertised), the "smog"
cam specs were 202 degrees duration @.050" (263 advertised) on the intake,
214 degrees @ .050" (293 advertised) on the exhaust.  Also, the overlap was
reduced to 38 degrees at .050".  The '70 390 and 401 cam had 297 degrees
intake duration, 304 degrees exhaust duration, and 69 degrees overlap, with
.457" lift at the valve, advertised.
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