On a small block chevy roller camshaft, how much would 1.6:1 rockers change the duration? Cam duration is 230/236, advertised 282/288. I am lead to believe it is small, but I want to know how much. Is there any type of formula I can use?
Can anyone answer this question
- Thread starter 84cutspreme
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rocker ratio dosent change duration. It raises the lift. U take yer lobe lift and multiply it by 1.6
it does change duration, too much ratio will open the valves too quickly and can cause valve float at high rpm. the guys I know who play with the ratios spend some time on a dyno to see what works best. You also have to be concerned with the higher pressures your putting on the studs and springs
I think you better throw out the book ya learned that from. Check this out
http://performancetrends.com/Definition ... -Ratio.htm
http://performancetrends.com/Definition ... -Ratio.htm
The rocker ratio changes the profile of the cam. You can't get the valve to open more without the valve opening earlier. That's just common sense. No battle here bill, I have yet to see a cam shaped like a pin
Yer not changing the camshaft at all. The only thing being changed is rocker arm geometry. I suppose it changes lobe sep angle and intake centerline too. lol
Im not a motor guru, so correct me if Im wrong....but I think duration is made purely by cam lobe design.... since the rocker is pushed by the rod, which is pushed by the lifter, which is pushed by the cam. It always starts w/ the cam lobe, and everything after that has only limited affects on the duration and lift, and without a longer duration on cam lobes, all you are getting is more lift with higher ratio rockers.... .02
bill... the higher rocker ratios was started by circle track guys who had to run a certain cam and they wanted more..the 1.6 rockers are still used by guys who cheat....
your right about the operation and since the rocker is a higher ratio when the cam starts to lift the rocker your getting more movement on the valve. It opens sooner and higher and closes later..
your right about the operation and since the rocker is a higher ratio when the cam starts to lift the rocker your getting more movement on the valve. It opens sooner and higher and closes later..
pontiacgp said:bill... the higher rocker ratios was started by circle track guys who had to run a certain cam and they wanted more..the 1.6 rockers are still used by guys who cheat....
your right about the operation and since the rocker is a higher ratio when the cam starts to lift the rocker your getting more movement on the valve. It opens sooner and higher and closes later..
From my understanding old rocket dog is right lol
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