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(EDIT) Advance the cam or not?

Discussion in 'The Garage' started by Codeman96, Jul 23, 2005.

  1. Codeman96

    Codeman96 1/2 ton status

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    I am putting in the Performer spec cam today and I am debating about putting it in with 9* advance up from the 5* it is if you put it in out of the box straight up. I already have a 3 keyway crank gear so its a matter of pulling it off and moving it.

    Running it through engine analyzer pro I will pick up little torque across the board. Should I mess with it? Any down falls to doing it?

    I need some input pretty quick I have all of the springs changed and I am about ready to start reassembly.
     
    Last edited: Jul 23, 2005
  2. rumbly truck

    rumbly truck 1/2 ton status

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    remember changing the position to the retarded side, will move the power up in the rpm band if you advanced it it will move it down. if you change it more than 4 degrees you should use a differant grind. i have a edelbrock performer in a 454 in a k-3500 and like it very much.
     
  3. Codeman96

    Codeman96 1/2 ton status

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    Yeah I was having a brain fart when I typed that. I was looking at advancing it not retarding it. After mulling it over I think I am going to put it in straight up and see how it runs.
     
  4. Mad-Dog

    Mad-Dog 1/2 ton status

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    Earn your degree in degrees.......

    Advancing the valve timing shifts the powerband around 500 rpm lower, Reatrding the valve timing shifts the powerband around 500 rpm higher.
    Essentially the cylinder pressures at a given rpm are moved lower or higher in the powerband, duration is in direct control of cylinder pressure at a given rpm so cams with large amounts of duration will have equate to low cylinder pressures at low rpm's and the the cylinder pressure will build as the cam "comes on the pipe" or the engine speed overcomes the excessive overlap and begins to breathe correctly.
    This is why the powerband of a particular engine can be determined by the duration at .050" valve lift.
    So to make a long story short advancing the cam will increase cylinder pressure at a lower rpm and place the engine in its powerband sooner.
    Most cam grinders "install" 4 degrees of advance into the cam so it is best to install the cam "straight up".
    But unless a degree wheel is used to check the accuracy of the "cam card" then 4 degrees plus/minus on the valve timing means nothing.........
     

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