Re: GM Cams
Stan:
Here were Jim's results:
Cylinder # 1 .050 check height
Part Number 3863143
Intake & Exhaust
Lobe center separation = 111.4 cam degrees
Valve Overlap = 13.9 crank degrees
Intake
Valve Opening = 8.6 œBTDC
Lobe Center = 111.4 œATDC
Valve Closer = 53.1 œABDC
Duration = 241.7 Crank Degrees
Max Cam Lift = .30516 In
Net Valve Lift = .500 In
Lobe Area = 27.36 In * DEG
Exhaust
Valve Opening = 57.5 ŒBBDC
Lobe Center = 111.4 ŒBTDC
Valve Closer = 5.3 ŒATDC
Duration = 242.8 Crank Degrees
Max Cam Lift = .32126 In
Net Valve Lift = .524 In
Lobe Area = 27.6 In * DEG
Notes: Intake .024 hot lash/ Exhaust .028 hot lash
Net Valve Lift=(Max Cam Lift x 1.72)- hot lash
Rocker Arm ratio= 1.72
I thought it was very interesting that a cam that is suppose to have a lobe center separation of 114 degrees cam out to 111.4. This car would idle a little rougher than a cam with 114 degrees. If you noticed that the camÃs exhaust lobe is a little taller than itÃs suppose to be. In a perfect world with a perfect cam the hot lash it should come out to .492. net valve lift. This imperfect grind on the exhaust side should be beneficial to some performance. I have the numbers of this cam at .020 which I'll post in the near future.
Like Jim, I am curious about the LSA difference, and the pretty big difference in intake/exhaust lift is worth noting as well.
Stan, any chance that you have a new "143" laying around that you could get checked @ .024"/.028" ? I haven't been able to locate a cam doctor in this part of the world yet...
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