I am planning on installing some FRPP Roller Rockers. Does anyone know what the ratios mean (I assume a larger ratio = greater lift stroke)? Also, will I need to replace the valve springs as well? If not, can I replace them anyway as well without problems?
i dont know too much about this but i dont think theyll help you out too much until u get a different cam that provides the lift to make the rockers effective. i know cams made for a supercharger setup will provide enough lift to use some rockers with a quite high ratio (1.80 is about the highest avaiable at least through supersix i believe)
for instance say a cam has a .300 lobe lift on the cam. that means the lobe is .300" higher than if it was a perfect circle also known as the base circle
multiply the cam lift .300 by 1.73 and that will give your valve lift of .519"
if you have 1.8 rockers then 1.8 X .300 = .540" valve lift
as you can see you get about .020" more lift with the 1.8's than the 1.73's which would equal maybe 7-8 hp increase
www.rpm-mustangs.com carries the harland sharp rockers. i have the 1.8 non adjustable. go with the adjustable rockers it makes a cam change much easier