[firewood]

I'm not sure how to even ask this question. I'm thinking about getting a new camshaft for my pickup.
My question is, for example: the lobe lift is .490 on both intake and exhaust. The rockers are a 1.6 to 1 ratio. I'm told that the valve springs can safely handle up to .500 inch lift and that there should be no problem with valve to piston clearance.
I know that the valve tip of the rocker is moving 1.6 times further than the advertised lobe lift of the cam. Are the springs good for only .500 inch or good for (.5 times 1.6 = .8) inch lift?

Sorry for this being so wordy. Just can't seem to get it out.
Thank you. Just trying to understand more about how these things work.

[RedRocket]

The springs are most likely good to .500" lift. The ".490" lift is probably valve lift, assuming a 1.5:1 ratio. If you're using 1.6:1 rockers, divide .490 by 1.5 (to find lobe lift) and then multiply the result by 1.6. This will give you your valve lift (.523") which is a little high for those springs. (Unless 0.490" was calculated using a 1.6:1 ratio???)

[firewood]

Thanks Red. When reading the cam specs saying, for example, .490" of lift, what rocker ratio are they using to get that figure?

[Vern Bradford]

Hi Firewood,
As Red stated the .490 lift was probably achieved using a 1.5:1 Ratio Rocker (1.5:1 is standard for small block chevy's). When GM lists their cams they will list it as: " Maximum Lift with 1.5:1 Rocker Ratio.
If you achieve .500 lift with a 1.5:1 Rocker Ratio or with a 1.6:1 Rocker Ratio it is all the same to your springs, they can't tell which one was used.
Vern Bradford