Hotrodpaul
11-02-2020, 12:42 PM
I recently decided to degree some of my GM NOS cams to see what they really have in terms of duration, lift, LCA, etc as compared to aftermarket cams. First cam up is the old Duntov 30-30 solid bumpstick, casting #9347, with .030" lash at the valve or .020" at the lifter with 1.5 ratio rockers. So I degreed the cam at the lifter at .020", .070", and .120" lift to be equivalent to a Hyd cam at 0, .050", and .100" lift. This would allow some apples to apples comparison. Of course, running the cam with a less lash would increase the duration and lift slightly. Here you go:
Intake:
Duration (Degrees) @.020" (251) @ .070" (207) @ .120" (176)
Centerline: 110 degrees
Lobe Lift: .295"
Exhaust:
Duration (Degrees) @.020" (253) @ .070" (208) @ .120" (178)
Centerline: 115 degrees
Lobe Lift: .295"
I was a little disappointed that the lift worked out to be only .450" or so with 208 degrees of duration at .070" tappet lift.
Next up will be the old Z-28, LT-1 solid cam for comparison.
Intake:
Duration (Degrees) @.020" (251) @ .070" (207) @ .120" (176)
Centerline: 110 degrees
Lobe Lift: .295"
Exhaust:
Duration (Degrees) @.020" (253) @ .070" (208) @ .120" (178)
Centerline: 115 degrees
Lobe Lift: .295"
I was a little disappointed that the lift worked out to be only .450" or so with 208 degrees of duration at .070" tappet lift.
Next up will be the old Z-28, LT-1 solid cam for comparison.