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  1. #1
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    Default Should I use 1.6 ratio rockers with this cam?

    Just thinking about getting some roller rockers (the budget comp cam ones), and wondering if I should get 1.6 ratio ones to get a little more out of the cam that's in it? I don't think I want to go the effort/expense of getting a new cam, so I'm trying to make the best of the current situation. The specs are in the image below, and I figure the lift would go from .444 with 1.5 to .474 with 1.6 rockers, so a little better. But I'm not sure what effect the ratio change will have on the rest of the cam's characteristics.

    Other than this, its a 20 thou over 350 with stock type flat tops (with valve reliefs), and a 3k stall apparently. Up to now it's had an edelbrock dual plane performer on it, but I also have a vic jnr here.

    Last edited by neRok; 10-05-2017 at 01:32 PM.

  2. #2
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    hi
    Look for dyno sheets for your combo . Look at the shape of the torque curve . Apparently tq curve is balanced around 220deg at .050 . After this the tq curve drops below peak tq and picks up after as u would expect . 220deg applies to 350cu in . I found this out by trying to pick a cam for a 400cu in ,which the balance point is around the 230deg mark .

    In regards to lift . Have as much as possible ! And have the lift to occur quickly at a very rapid rate . eg aggressive roller cam
    Lift once calculated net at lobe and gross at valve needs to match cylinder head fitted for best results . U have heard of ""all components matching "" [to get the best result possible ] ,this is just 1 part of the big picture .

    Use KNOWN engine combo sheets as a good guide Eg start with the elderbrock street combos
    Beaware that engine dyno`s results can vary depending upon type and operater input

    I matched my gross lift to take into account max potential of cylinder head . Of course the remainder of valve train has to be able to handle it also . In my case I am running out of valve spring travel so I have only enough spring for another .025` lift /5-10 deg of duration upgrade

    Most rockers will have an RPM limit / valve lift limit / spring pressure limit / spring diameter limit . Beaware many cheaper rockers are very limited .

    Vehicle use plays a big part in car setup strip or street ??? If u donot have the gearing for eg u will not use the full benefit of the extra hp/tq , the same applies to stall speed .
    Last edited by swampy; 11-05-2017 at 09:37 AM.

  3. #3
    Do you ever leave? paulzig's Avatar
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    It wont hurt but it probably wont help a whole lot.

    Time the cam using the .050" numbers given, the ones at SAE .006 arent right.

  4. #4
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    Quote Originally Posted by paulzig View Post
    It wont hurt but it probably wont help a whole lot.

    Time the cam using the .050" numbers given, the ones at SAE .006 arent right.
    It's already been in for a years and running good, so I will presume its timed correctly. What do you reckon about the vic jnr? It seems you usually recommend them, but maybe this engine is too stock?

  5. #5
    Do you ever leave? paulzig's Avatar
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    The Vr junior, single plane and shorter runners will act like more duration on the cam and it will extend the RPM range. it will take from the bottom end and add to the top end. The cam is a low lift, older, lazier ramp rate so airspeed will suffer a little bit. But I would put the Vic Jr on.

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