Valve spring / Cam question
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From: Houston, Texas
Valve spring / Cam question Ok, so if I read the right information then a cam with say a .500 lift coupled with 1.5 rockers would be .750 lift on the valves right?
How come I usually see heads rated to like .700 lift max if the majority of performance engines would need higher lift?
I missed something, what was it?
How come I usually see heads rated to like .700 lift max if the majority of performance engines would need higher lift?
I missed something, what was it?
Last edited by Will Clark; Jan 26, 2004 at 02:35 PM.
Originally Posted by Will Clark
Ok, so if I read the right information then a cam with say a .500 lift coupled with 1.5 rockers would be .750 lift on the valves right?
How come I usually see heads rated to like .700 lift max if the majority of performance engines would need higher lift?
I missed something, what was it?
How come I usually see heads rated to like .700 lift max if the majority of performance engines would need higher lift?
I missed something, what was it?
Thread Starter
TECH Resident
Joined: Oct 2002
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From: Houston, Texas
Originally Posted by Paul @ Thunder
If the LOBE lift of the cam is .500 then yes you will see .750 at the valve. Most printed specs will be VALVE lift with a given rocker ratio. Say if you are looking at a cam in Comps catalog that says .500 lift then that is with a given rocker arm ratio, like 1.5. So .500 lift with 1.5s would be .533 with 1.6 ratio rockers, and so on. About the only time you see lift quoted at the lobe would be on a cam doctor report. Hope this helps.
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From: Los Angeles
Yup, Paul nailed it...most LS1 cams have about 0.330-350'ish thousanths of lift ground into them, which when coupled with our stock 1.7 ratio rockers you get 0.560-0.595'ish valve lift.
When comp lists cam specs for an LS1 cam, they generally state on the cam card they are with a 1.7:1 rocker being used.
When comp lists cam specs for an LS1 cam, they generally state on the cam card they are with a 1.7:1 rocker being used.
