Advertised cam duration 0.006" or 0.004" lifter rise
Posted: January 11th, 2012, 11:16 am
Profiled my stock 2001 cam the other day. Specs were generally within a degree of those published. 
But...
Don't most aftermarket companies spec their advertised duration at 0.006" lifter rise?
The stock cam only matched published specs at 0.004" lifter rise. That makes comparison with other cams more difficult.
My results:
Intake duration at 0.004"= 252 deg (published = 253.3 deg)
Intake duration at 0.006"= 243.5 deg
Intake duration at 0.050"= 189 deg
Exhaust Duration at 0.004"= 258.5 deg (published= 259 deg)
Exhaust Duration at 0.006"= 251.5 deg
Exhaust Duration at 0.050"= 192 deg
Calculated centerlines were right on when using .004 and .006" points, but lobe centerline shifts when using the 0.050" open/close points.
Max lift is also shifted from the published centerlines.... apparently the lobe is asymetrical.
But...
Don't most aftermarket companies spec their advertised duration at 0.006" lifter rise?
The stock cam only matched published specs at 0.004" lifter rise. That makes comparison with other cams more difficult.
My results:
Intake duration at 0.004"= 252 deg (published = 253.3 deg)
Intake duration at 0.006"= 243.5 deg
Intake duration at 0.050"= 189 deg
Exhaust Duration at 0.004"= 258.5 deg (published= 259 deg)
Exhaust Duration at 0.006"= 251.5 deg
Exhaust Duration at 0.050"= 192 deg
Calculated centerlines were right on when using .004 and .006" points, but lobe centerline shifts when using the 0.050" open/close points.
Max lift is also shifted from the published centerlines.... apparently the lobe is asymetrical.