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what ratio for my roller rockers?

Discussion in 'The Garage' started by bigoltrux77, Nov 12, 2002.

  1. bigoltrux77

    bigoltrux77 1/2 ton status

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    im going to be investing in roller rockers soon for my modified small block. I have no clue what the 1.5, 1.6 etc means on the ratio. What is the best? What should i get?
     
  2. Klink K5

    Klink K5 1/2 ton status

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    How muck total lift do you want at the valve when camshaft it at the top of the ramp? What I mean is if you have a camshaft with advertized lift with 1.5 rockers and the lift at the valve is .500, a 1.6 rocker will yield .532 lift with the same camshaft. I hope this sends you in a generla direction. /forums/images/graemlins/thumb.gif /forums/images/graemlins/k5.gif Basically ratio is the multiplied fulcrum of the rocker. Odviously,the 1.6 is longer than the 1.5 so you will get more lift from a 1.6 . Comp cams sells a decent rocker or Harland Sharp is also good for the money!
     
  3. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    I've got 1.7 ratio Harlon Sharpe roller rockers on my BB. Very nice. /forums/images/graemlins/smile.gif
     
  4. zakk

    zakk 1/2 ton status

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    roller rockers generally need to have an eye kept on them. I remember reading on here that they are good for about 30k miles.

    On a BBC, 1.7 is stock.

    On a SBC, 1.5 is stock. 1.6 will require taller valve covers and might need upgraded springs, depending on the manufactures recomendations.
     
  5. HarryH3

    HarryH3 1 ton status Author

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    Talk to the tech folks at the company that made your cam. They can recommend the correct ratio for your application. The ratio just tells you how the lift of the cam is modified by the rocker arm. A lift at the lobe of .100 inch will translate to .150 inch of movement of the valve with a 1.5:1 rocker arm ratio and .160 inch with a 1.6:1 rocker arm ratio. But if you already have a cam that provides a lot of lift, then going with too high of a rocker arm ratio can cause the coils in the valve springs to bind at full valve lift. That will wipe out the cam in just a few seconds. /forums/images/graemlins/frown.gif

    1.5 is the stock rocker arm ratio for small blocks, while 1.7 is found on 454's. Small blocks with a small cam can sometimes wake up just a bit with a 1.6:1 ratio, but I've also seen where it actually hurt performance. Some engines perform best with mixed ratios, depending on the cam and head flow characteristics. I've seen dyno tests that showed small blocks performing best with a 1.5 ratio on the intake valves and 1.6 on the exhaust valves. That's why you want to talk to the cam folks. They've done a lot of testing and can help you determine the best setup for your particular engine. /forums/images/graemlins/cool.gif
     
  6. GMslave

    GMslave 1/2 ton status

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    <font color="red"> WARNING!!! </font color> If you are running Vortec heads, you better make sure that you get "self aligning" rockers. I have the GMPP ones, but I think some aftermarket ones are available too.
     
  7. chulisohombre

    chulisohombre 1/2 ton status

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    i have the crane cams roller tip 1.6 lift rockers.it definitely upped my power pretty good and the valves run a lot smooother than a stock rocker arm.i have heard problems with some heads and not having the self aligning rockers.someone was saying that is the pushrod hole is square you are alright without self aligning,and if the hole is circle you have problems with the pushrod not aligning right and someone said they bent a couple of pushrods and the engine shop he talked to told him this.im thinking if you already have a performance cam you will not need the extra lift of a 1.6 rocker because the cam will already lift higher or longer than stock depending on the grind and lobe shape.
     

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