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cam numbers

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by possum, Feb 6, 2002.

  1. possum

    possum Registered Member

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    I'll admit it now... I don't know jack about the numbers for a cam. I'm looking for a good low end towing/ torque set up. Which numbers should I be looking for? I don't know what they mean and it may as well be stock market information.[​IMG]
    78 Blazer, 350, th350, np203, 4" lift.
    need anymore info?

    <a target="_blank" href=http://community.webshots.com/user/possum1970>78 K5</a>
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  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    If you don't know what the numbers mean then an educated cam choice will be difficult.

    The are two basic sets of numbers though and they tend to give you a ballpark idea of a cam's abilities. Duration which is usually expressed two different ways. Advertised duration, expressed in degrees but usually measured in different ways by different manufacturers. Duration numbers should always be compared at 0.050 of lift...a stock cam will generally have just under 200 degrees of duration at 0.050. A performance cam will have longer duration which just means the valve will stay open a little longer than before.

    The second set of numbers to watch are valve lift numbers. Valve lift is how far the cam will open the valve. A stock cam may be in the .380" lift area...performance cams generally have lift number of .400" and up.

    Honestly if I had limited knowledge of cam's I'd call the tech lines of a few cam manufacturers and tell them what I was looking for performance wise. They will ask a few questions about your motor and truck and make a recomendation. I did this with my last cam choice and was quite happy with the results.

    Rene

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  3. possum

    possum Registered Member

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    Thank you. Now I know what the numbers mean. I got a new wrinkle now.[​IMG] I just have to call and find out which are good for pulling power. Thank you.

    <a target="_blank" href=http://community.webshots.com/user/possum1970>78 K5</a>
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  4. txbartman

    txbartman 1/2 ton status

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    Not too long ago I was in your same boat. I did exactly as Rene suggested. I called CompCams, Crane Cames, and Summit Racing. Told them what I had and what I wanted. They each recommended a particular cam. I then compared the actual specs of each of the cams and then called them back later to discuss if there were big differences between the recommendations.

    No one knows cams like the manufacturers themselves.

    Brian
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  5. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Generally you'll want a mild cam for low end torque. Ask about Comp Cams Extreme energy cams. They have very aggressive lift ramps and are dual pattern cams. Dual pattern usually means the exhaust valve will have a slightly different duration and lift than the intake. This can allow a motor with restrictive heads to breathe better...

    It's better to go too mild than too big with a cam choice.

    Rene

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