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Thread: Adjusting valves cold ?

  1. #1
    Senior Member DYNO OPERATOR
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    Adjusting valves cold ?

    Hey guys,

    I remember there was a discussion on this subject before but I can't find it. When you are adjusting valves on a roller cam with the engine cold, do you adjust it a little tighter or looser than your supposed to. I appreciate yall's help.

  2. #2
    Member JUNIOR BUILDER
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    A tad looser to allow for the parts expanding when they come up to temp. I generally lash at 0.022 cold, 0.020 hot for my cam.
    -Tanner

  3. #3
    Senior Member DYNO OPERATOR
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    Thanks Tanner,

    Thats what I did, just wanted to make sure.

  4. #4
    Member JUNIOR BUILDER
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    Re: Adjusting valves cold ?

    Quote Originally Posted by bowtie4542001
    Hey guys,

    I remember there was a discussion on this subject before but I can't find it. When you are adjusting valves on a roller cam with the engine cold, do you adjust it a little tighter or looser than your supposed to. I appreciate yall's help.
    Adjust them hot as you normally would and then let it sit over night and check where they are at to get YOUR cold settings

  5. #5
    Member JUNIOR BUILDER
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    OK now I'm confused. I too used to think you would adjust them looser because things would expand and tighten up, then I swear I heard the because the block and heads actually grow that the tolerances actually increase.

    The only reason this even started to make sense was beacuse how much my block grows when warm as evidenced by my blower belt getting tighter.

    Too many margaritas?

    FWIW I always adjust mine hot and have burns to show for it.
    The show queen gets crowned...6.32@111

  6. #6
    Member JUNIOR BUILDER
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    With iron block and iron heads, add .002"
    With iron block and aluminum heads, subtract .006".
    With both aluminum block and heads, subtract .012

    I knew it was somewhere. This is what I used on initial startup to get close.
    The show queen gets crowned...6.32@111

  7. #7
    Senior Member RACING JUNKIE
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    margaritaman, is very close on his startup,

    Having been in the machining trade almost 50 yrs. there are growth differences in how metals grow and contract.

    example: STEEL grows approx (.0001) per 10 degrees temperature change.

    example: ALUM grows approx (.0007) per 10 degrees temperature change.

    But other factors come into play, such as copper head gaskets, alum rockets, steel blks, alum heads etc.

    Most solid cams set between .020 and .030, so the best method is too always set them loose, maybe .030 warm the car up to running temperature and reset them correctly and never run a car on the initial setting.

    margaritaman is right about the blower belt tightening up and nothing will eat an idler pulley bearing or break a blower belt quicker than a overtight belt.

    just my .02 cents

    Zip.

  8. #8
    Senior Member MASTER BUILDER
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    Rocker ratio plays an important part as well.with an aluminum block and heads on our SB2.2 engines using 1.9 int ratio and 1.85 ex.the int set at .018 hot will be .002 negative cold, the in valve is actually open. aluminum expands at .001 per inch of length for each hundred deg. steel expands at roughly .005 per inch per hundred.Bill
    Hendrens Racing Engines
    1310 U.S. Hwy 221 North
    Rutherfordton N.C. 28139
    828-286-0780 Bill, Steve, Mike
    www.hendrensracingengines.com

  9. #9
    Senior Member DYNO OPERATOR
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    Thanks Guys,

    What is the best way to set valves. I thought I was going down the right path but this weekend proved I was wrong. Also is there a different way to adjust valves if you are running a stud gridle? Thanks

  10. #10
    Senior Member MASTER BUILDER
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    When using a stud girdle you just loosen it enough so you can turn the adjuster nut.studs on most heads aren't dead on as far as alignment so if you loosen the stud girdle all the way,set the valve and tighten it the valve lash changes.Bill
    Hendrens Racing Engines
    1310 U.S. Hwy 221 North
    Rutherfordton N.C. 28139
    828-286-0780 Bill, Steve, Mike
    www.hendrensracingengines.com


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