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Cam size in relation to Cubic inches

Discussion in 'The Garage' started by mountainexplorer, Jun 29, 2005.

  1. mountainexplorer

    mountainexplorer 1/2 ton status

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    I have a Comp 280 cam that was in a 396. It has .516 lift I believe... can't remember lobe separation angle. But anyway, it had a slightly rough idle in the 396 that was .030 over.

    I just pulled a cam out of a .060 over 454, which had a smooth idle and I had assumed it had a stock or RV cam in it. However, visually, they look identical. I know that the only way to tell for sure is to mic it.

    But if they are the same cam, is it just the difference in cubic inches that makes it sound milder in a 468 vs. a 402?
     
  2. Mad-Dog

    Mad-Dog 1/2 ton status

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    The same cam in a bigger engine will be milder....if it is indeed the same cam.
     
  3. sled_dog

    sled_dog 1 ton status

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    yes more cubic inches, means milder idle with a bigger cam. However, to really tell the specs of the camshaft requires a dial indicator not a mic. Cam lift means squat compared to duration. I know I can't look at a cam and tell you how much duration it has, doubt you can either. Can you really tell the difference between say 30 degrees, with your eyes? Best bet to figure duration, is to put a dial indicator on top of the pushrod and slowly spin the cam over. You need to put a degree wheel on the front of the cam. Place the marker at zero when the cam is on the base circle(the part of no lift). Spin it over, note where the cam starts to lift the valve, and where it stops lifting. Take that and figure the degrees of camshaft duration. Do you care that much? I'm not a fan of reusing cams, but thats me, I get paranoid after having a few "mildy used" engines blow up. Of course I know you put things together I'd be scared to death to do with great success.
     
  4. mountainexplorer

    mountainexplorer 1/2 ton status

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    I'm estimating this motor to last me one weekend. I thought about buying a new cam and lifters yesterday, but that takes more money and it'll probably get ruined anyway. So I'll just use what I have.

    The one I know is a Comp 280 has "280" stamped on the end of it, as well as the number "1005R". The unknown cam from the 454 also has "1005R" stamped on the end of it but no indication of duration.
     

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