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Old 03-10-2013, 12:21 PM
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We don't know specifics on your build? What ratio rockers are you running?

You could try 1.6 ratio rockers on the exhaust only! It may increase the cylinder evacuation and velocity! If your running 1.6 now on all your valves you can try going to 1.5s on the intakes!

You can increase the lift of an existing cam profile by going to a higher rocker arm ratio. A small block Chevy where the cylinder head runners are not maxed out may benefit from moving up from the stock 1.5:1 ratio to 1.6:1 rockers. But be careful going up more than one tenth in rocker ratio can lead to trouble; there's a limit to how fast you can move and accelerate the valve before the valve spring (that's correct for that cam) can no longer control the system. If a profile was a good design with 1.5:1 rockers, and performance increased at 1.6:1 it'll probably be unstable with 1.65:1 or higher rockers. The correct solution is to design a custom cam profile from the ground up for use with higher ratio then 10% 0ver normal ratio! Over the counter cams are designed for a standard ratio or 10% over rocker any ratio over that design changes spring flex, harmonics, compressed spring pressures seat speed etc!

Special custom ground cams can slow the speed of the valves that high ratio rockers create on over the counter cams!

Myself I run high ratio rockers on the exhaust only that's just my preference but it depends on flow, I start with standard rockers run it and then go higher in ratio run it again, and if performance picks up I'll stay with the higher ratio rockers, if performance doesn't increase Ill drop back to a lower ratio! I don't build an engine and order a cam and put higher ratio rockers on it without knowing the downside or benefits of the rockers! Ive seen too identical builds and higher ratio rockers will benefit one engine and not the other.

Jester
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