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Comp Cam 276AH-10 Part # 51-309-4

Discussion in 'COMP Cams Support Forum' started by beertracker, Nov 12, 2018.

  1. beertracker

    beertracker New Member

    Joined:
    Oct 24, 2013
    I have decided to use this cam, Comp 276AH-10 Part # 51-309-4 in my Pontiac 455. Do you recommend this cam be advanced? If yes, how much? Does the cam come with ground in advance from the factory? How much?

    bt
     
  2. beertracker

    beertracker New Member

    Joined:
    Oct 24, 2013
    Are there Comp Cam employees on this forum who can answer my question? Or is this a customer only forum? I am starting to think I have chosen the wrong Comp Cam contact method.
     
  3. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    COMP employees haven't been active on this forum in several years. I can, however, answer your question as well as they would. This cam has the recommended advance ground into it. Therefore, they recommend using a timing degree wheel to properly set the timing gear at 0 degrees during installation.
     
  4. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Cam is degreed 4 degrees advanced from the factory.
     
  5. beertracker

    beertracker New Member

    Joined:
    Oct 24, 2013
    A A, thanks for the info. OK, I already bought a timing gear set that allows 0, 4 advanced and 4 retard but am considering exchanging it for one that has the previous settings and 2 advanced and 2 retard. When using a timing degree wheel to achieve 0 deg you don't how much crank sprocket adv or ret will be required. I suppose it's a matter of trial and error.

    I haven't had much luck getting answers from Comp. I have tried submitting a message through their web page and never receive a answer. They must be deleting messages. I tried chatting with them but the agent didn't seem very knowledgeable.
     
  6. beertracker

    beertracker New Member

    Joined:
    Oct 24, 2013
  7. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    If you work with the provided opening and closing numbers for the intake and exhaust, you can determine the factory degree setting from "0". The cam is four degrees advanced. This is also the usual setting COMP grinds in. 2 degrees to account for eventual timing slack plus two. It's better to stay with the factory setting. Each 2 degrees equates to roughly changing the power band up or down by 500 RPM. If you need to change this from the factory setting by more than two degrees either way, you are likely choosing the wrong duration camshaft. Raising the advance invites low RPM detonation and lower the high RPM power band. Retarding the cam will lower low RPM detonation tendencies, and raise the RPM power band higher..
     
  8. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    This is a two pattern camshaft. I believe Crane was the first to depart from grinding single plane race cams in the 70's. COMP also now grinds four pattern cams. Single pattern cams made finding the factory advance/retard setting easy. With the added patterns, it's more difficult to determine. If you could get Matt Maxwell on the phone at COMP, he would tell you all you would ever need to know about camshaft design questions. The old COMP Cams catalogs used to tell how to determine what I already told you. I don't know if the new catalogs do.
     
  9. beertracker

    beertracker New Member

    Joined:
    Oct 24, 2013
    Great info & thank you. Matt Maxwell, I haven't heard that name in a long time. I remember him on this forum a few years ago.

    Since the cam is 4 deg advanced from the factory I will use this setting and place the dots in line with each other. My timing set has 0, 4 adv and 4 ret keyways. I am planning on degreeing the cam and I can't predict if he cam is will be on spec with dots lined up. I wonder if I should buy a timing set that has keyways for the above plus 2 adv, 2 ret, 6 adv and 6 ret just in case they are needed?
     
  10. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Well, after the engine is running you would be able to tell if the engine needs added retard, if the compression is high and the fuel octane is too low, to prevent part throttle detonation. I see no real need to advance the cam from a "0" degree gear setting as that could cause a problem. If two degrees cam retard isn't enough in this scenario, you will need a different cam with more overlap. A custom grind may be more satisfactory for your intended use. You really just need a timing gear setup that satisfies the "0" degree timing gear setting using a degree wheel. All timing gear brands are also not ground to satisfy a "0" degree timing gear setting. Your engine characteristics could also allow some change. It could take a gear with 2 or 4 degree gear settings to give you a true "0" degree timing gear setup that allows the cam to run at the factory ground 4 degree advance setup.
     

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