CAMSHAFT BREAK IN spring pressure

Discussion in 'Big Block Cadillacs' started by Caddy123, Mar 31, 2018.

  1. Caddy123

    Caddy123 Member

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    Hello Guys i wil run in a comp 270H cam .510 lift 270-270 @.050 224-224 110 sla.
    I have perfect single springs for it mts ss/c set on 1.800 spring height 120-320 lbs.
    Run in the cam with this pressure i tink to high!!
    If i set the open pressure to 270 lbs my closet pressure is 60 lbs, but than must i make shims bymeself its difficult.
    Can i break in the cam with stock springs 70-150 lbs or is this to low spring pressure.

    Thanks for help gr Danny
     
  2. Darius

    Darius Well-Known Member

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    Danny,

    There are several truly expert posters on this forum who will be able to provide you information with knowledge behind what they say. But from my limited understanding I don't see a problem breaking in that camshaft with the MTS springs. Just be sure to liberally apply the break-in fluids suggested by the manufacturer and also "dope" the engine oil with a break-in additive. Follow the instructions as to time and RPM and all should be well. Oh, be sure to have an oil pressure gauge where you can monitor what's happening during the process.

    Now to hear from guys who know a ton more than I do.

    Best,

    d
     
  3. Caddy123

    Caddy123 Member

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    OK thanks Darius compcams reccomends max 270 lbs open, and i want no damaged cam!!! So im asking on this forum.
    Gr Danny
     
  4. Darius

    Darius Well-Known Member

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    See, I told you I didn't know what I was talking about!

    d
     
  5. dave brode

    dave brode Well-Known Member

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    Imo, if you will have 320# open, they too stiff. I doubt that it needs even 300# open.

    http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=52&sb=2

    You wrote .510" lift. Since comp uses the wrong rocker ratio to calc' lift, you need to multiply rocker ratio by the .300" lobe lift. With 1.65-1 rockers, it's .495" .

    Fwiw, I ran a 292/302, 232/240, .536" with GM beehives at 95# closed and 295 open. Saw 5500 in the water box a few times, with no signs of float. Even with a straight spring, imo, 100/300 would be enough for that cam.

    You can run as little at 60# closed if rpm is limited to 2500 for break-in.

    Dave
     
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  6. Darius

    Darius Well-Known Member

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    Thanks Dave!!! About time someone with knowledge show up and share their wisdom - and there couldn't be a better person than you! :D

    bro. d
     
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  7. Caddy123

    Caddy123 Member

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    Im a little carefull i destroyed 2 times my engine with a rebuild, mistake from new wrong parts from Companys!
     
  8. Darius

    Darius Well-Known Member

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    Caddy 123,

    I understand and appreciate your caution as I too have had the misfortune of using parts that caused a lot more grief then go. The double whammy is that its OUR money that paid for those parts that then cost us even more!

    d
     
  9. Caddy123

    Caddy123 Member

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    Thanks Dave i have 1.70.roller.rockers.
    So its 0.510 lift .
    Hope i have enough room on the valve guides.
    Thanks al for help
     
  10. 8ad-f85

    8ad-f85 Well-Known Member

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    Should be able to trim the guides before assembly if needed (There's usually more room than that).
    Adding to Dave's post... there have been cam cores found to be soft in the past.
    I'd be careful about how much pressure run over-the-nose.
    I'm not sure if your cam source would have ever been at risk.
     
  11. Caddy123

    Caddy123 Member

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    Thanks for all tour tips.
    Dave i set them to 100-300 lbs thanks
    Thanks gr Danny
     
  12. dave brode

    dave brode Well-Known Member

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    If you have std locks, you could run a +.060" lock to back them off a bit for break in.
     
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  13. Caddy123

    Caddy123 Member

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    Dave i have set the springs with with .060 shims 18.50 height.
    Run in without shims on 19.10 height.
     
  14. dave brode

    dave brode Well-Known Member

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    Going by your open closed #s, springs are 392#/inch.

    Removing .060" shim would reduce open pressure by 12#. [both open and closed]

    Using +.050" locks would reduce pressure by 10#.
     
  15. Caddy123

    Caddy123 Member

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    Thank you very much Dave
     
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  16. dave brode

    dave brode Well-Known Member

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    glad to help
     

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