Allright guys, I got this cam off of some dude over tthe net and I wanted to check the lift to make sure it was legit. I picked up my sliding caliper and measured the base circle the best that I could and it measured out to be 1.233" and then I measured from the tip of the lobe to the back of the base circle and it measured 1.542". Then when I measured my LO3 cam the base circle came out to 1.335 and the lobe came to 1.589. The Lt1 came comes out bigger if you subtract the difference but is this right and why is the base circle bigger on the stock LO3 cam?

 

Cam from Some dude
1.542-1.233 = 0.309 inches lift

LO3 cam
1.589-1.335 = 0.254 inches lift

These are both lobe lifts so you have to multiply by 1.5 to get the lift at the valve:

LT1 cam (from Dude) = 0.464 inches
LO3 cam = 0.381 inches

These are both close enough to the factory values for lift, i.e. they are within any measurement error or manufacturing tolerance, or both. As far as why the base circle is larger on the LO3, it's becauseif they made the base circle any smaller than what they have, and kept the same lift, they would need longer pushrods. GM likes to use the same pushrods for many applications, so they intentionally use a smaller base circle on hotter cams having higher lift. If you think about it carefully, it makes sense. HTH.

 

thanx alot man, that sure explains it.