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Playing "matching" with 2 cams and 2 motors... what would you run?

Discussion in 'The Garage' started by mountainexplorer, Oct 13, 2005.

  1. mountainexplorer

    mountainexplorer 1/2 ton status

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    I have 2 cams for big blocks.

    One is a Comp High Energy 268 duration, .485 lift.

    The other is a Comp Extreme 4x4 262/270 duration, .505/.515 lift

    The two motors are:

    454 bored .020 over, 781 casting oval port open chamber heads, in an '82 Stepside running 4.10 gears Detroits front and rear, and a 4spd... to be driven on the street as well as off road with 35" tires and occasionally 39.5's. This 454 currently has a .485 lift but 290something or higher duration cam, with two lobes going flat... so the valve springs should handle the 268 High Energy cam.

    402 all standard as far as I know right now, out of a motorhome, open chamber oval port heads, that will be going into a '76 K5, 4spd, 4.56 gears, locked front and rear, on 38's, off-road only, never to see pavement, trails and mud only.

    What cam would you match with what motor?
     
  2. 3 on the tree

    3 on the tree 1/2 ton status

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    I think that the higher lift cam will cause coil bind in either engine, but I can't remember for sure what the lift limits are for stock valve and spring set up. Usually, the higher compression motor will work better with the greater duration, I am assuming that the 402 has the higher CR. BUT, more CI also helps tame long duration cams. If it was me, I would put the higher lift cam in the 402 and lettr wind up.
     
  3. thor

    thor 1/2 ton status

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    The 268 in the 402, the extreme in the 454. Neither is particularly wild, but the lift and longer exhaust duration will help out with the bigger cubes. Coil bind won't be an issue with either cam, but if your springs are worn out they can break and will float your valves.
     
  4. mountainexplorer

    mountainexplorer 1/2 ton status

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    I'd be replacing valve springs in whatever I put the .505/.515 lift cam in.

    The 454 should have flattop pistons... the 402, being a 1972 motorhome motor I would think would have flattops and not domed pistons. Heads are about the same in chanber size, so compression ratios should be pretty close between the two motors.

    I need to pull the motorhome 402 apart to tell for sure. I have the two cams and am ready to swap one into the Stepside's 454, but keep debating over which I should put in it now, and save for the 402 in the spring when I deal with it.
     
    Last edited: Oct 14, 2005

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