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my lift is .518 intake and .543 with 1.6 ratio rockers but im wanting too go 1.65 or 1.70 rockers but i dont know how much more that will make my lift
To find out what the change would be with different rocker ratios, you need to find out the lobe lift on the cam. If you don't have the cam card with this info, just take your lift with the 1.6 and divide it by 1.6, then multiply by the new ratio you want to compare. Example: .518 divided by 1.6=.32375, which is your lobe lift on the cam. Now multiply .32375 by the ratio you want to run, we'll say 1.7 and you get .550 on the intake. Do the same thing on the exhaust and you end up with roughly .577 lift.
 

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Valve spring selection isn't that simple and unfortunately the kits you gave don't give the necessary info to answer your question. Lift is only one spec and you can't buy valve springs based on the lift alone. With the info you have, the 1.8 installed height should have the potential for .050 more lift than the 1.75 installed height, but this is only true if they have the same coil bind height. The best way to go about this is to find out what your cam manufacturer recommends for seat/open pressure and spring rate, then match O.D. size and do the math to find out what lift you can run. For instance, if a spring has an installed height of 1.8" and a coil bind height of 1.150, then there is .650" worth of lift before coil bind height. Depending on the application, you at least want another .060" clearance before coil bind, so with those specs, you could run a max of .590" lift with that set up (1.8-1.150=.650"-.060 minimum clearance=.590")
 
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