[JLerum]

Well, I have returned with some results for an LS-6/L-72/L-78 cam. Tuesday I made the trip over to a friends business that has a cam doctor. This equipment is unique in that it will measure a cam at derived points selected by the operator. All measurements are made and printed out on a PC.

The cam that was used was purchased from GM in Dec of 1982. I think youÃll be surprised by the tolerances of this 3863143 cam. The printout from the cam doctor came out as such.

************************THE CAM DOCTORÃS ANALYSIS****************

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.


Jim