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Unit 5302 · 11-21-2004, 01:16 PM

Stock cams have .444/.444 lift. With 1.7s, it will be .472/.472, still well within the .500 max lift for the stock springs, but with the higher lift, high rpms may see increased valve float.

Duration is changed by changing the ratio of the rockers, just not very much.

Since duration is measured at either .003 (Ford advertised) or .050 lift, the amount of time the valve lift is at that .003 or .050 will be changed. I doubt it would be enough to report an extra degree on the .003 simply because you're dealing with such a minor multiplier (1.0625) when going to 1.7s.

E-303

.498/.498 220*/220* @ .050 Adding 1.7s opens the valve just a little more than what it used to be open so when it was at .048 of lift before (and not counted for duration), it'll now be at .050 (and counted for duration). You may see another degree or two of duration or so.

11-21-2004, 01:16 PM	#7
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	Re: what rockers? Stock cams have .444/.444 lift. With 1.7s, it will be .472/.472, still well within the .500 max lift for the stock springs, but with the higher lift, high rpms may see increased valve float. Duration is changed by changing the ratio of the rockers, just not very much. Since duration is measured at either .003 (Ford advertised) or .050 lift, the amount of time the valve lift is at that .003 or .050 will be changed. I doubt it would be enough to report an extra degree on the .003 simply because you're dealing with such a minor multiplier (1.0625) when going to 1.7s. E-303 .498/.498 220/220 @ .050 Adding 1.7s opens the valve just a little more than what it used to be open so when it was at .048 of lift before (and not counted for duration), it'll now be at .050 (and counted for duration). You may see another degree or two of duration or so.