Page 1 of 5 123 ... LastLast
Results 1 to 10 of 43

Thread: Valve Lash and Cam Timing

  1. #1
    Senior Member MASTER BUILDER
    Join Date
    Aug 2007
    Location
    Iowa - USA
    Posts
    218

    Valve Lash and Cam Timing

    How does the valve lash effect the cam's valve timing? For example, i bought a engine with a Lunati solid lifter cam. The valve lash for both intake and exhause is.030. What does this do for the engine?

  2. #2
    Senior Member EXPERT BUILDER
    Join Date
    Nov 2008
    Posts
    263
    looser valve lash will give u more top end, tighter will give u more torque of the bottom

  3. #3
    Senior Member DYNO OPERATOR
    Join Date
    Jan 2004
    Location
    central Illinois
    Posts
    459

    valve timing

    Are you sure about that? Loosening the valve lash makes the cam seem smaller, which helps bottom end performance. Tightening makes rthe cam seem larger, which helps the top end. That has been my experience.

    If you play with lash up to .004 looser and tighter, you may find minor improvement. It will also tell you if cam you have is too large or small if it wants lash set different than factory setting. I set lash .006" tighter cold than hot specs for BBC with aluminum heads and iron block.

  4. #4
    Senior Member DYNO OPERATOR
    Join Date
    Apr 2008
    Posts
    504

    Wrong

    Quote Originally Posted by bowhay
    looser valve lash will give u more top end, tighter will give u more torque of the bottom
    This advice given above is exactly wrong. More lash gives less duration and tighter gives more duration. More duration will enhance the top end and likely remove some from the bottom end. You must respect the manufactures intended valve lash and not deviate more than .010" either way, too louse a setting will hammer the lifter off the lobe causing damage.
    Bruce

  5. #5
    Senior Member RACING JUNKIE
    Join Date
    Sep 2007
    Posts
    4,143

    Re: Wrong

    Quote Originally Posted by TopspeedLowet
    Quote Originally Posted by bowhay
    looser valve lash will give u more top end, tighter will give u more torque of the bottom
    This advice given above is exactly wrong. More lash gives less duration and tighter gives more duration. More duration will enhance the top end and likely remove some from the bottom end. You must respect the manufactures intended valve lash and not deviate more than .010" either way, too louse a setting will hammer the lifter off the lobe causing damage.
    Bruce

    X2....I know first hand about the roller damage. I used to think they would tighten up when HOT...of course this is 100% wrong but back then I didn't know...I set them cold just a little loose thinking they would be just right when hot....it's the opposite.I busted a roller lifter(and a block) after 20 something passes. live and learn.

  6. #6
    Senior Member RACING JUNKIE
    Join Date
    Jul 2007
    Location
    Independence, Missouri
    Posts
    1,188
    Would anyone care to elaborate, on the "correct" way to adjust valve lash? :twisted:

    I'll get the popcorn, and drinks.
    No matter where you go, there you are.
    **IN GOD WE TRUST**

  7. #7
    Senior Member RACING JUNKIE
    Join Date
    Sep 2007
    Posts
    4,143
    Quote Originally Posted by suicidebomb
    Would anyone care to elaborate, on the "correct" way to adjust valve lash? :twisted:

    I'll get the popcorn, and drinks.
    :lol: I remember that...

  8. #8
    Senior Member RACING JUNKIE fla1976's Avatar
    Join Date
    Aug 2007
    Posts
    1,530
    This is how I adjust valves. The website has excellent info on valve adjustments but there is too much info to list here.

    http://www.centuryperformance.com/ad...h-spg-149.html



    Valve Adjustment Procedure - The Quick and Accurate Way:
    First, view this little chart below for Small and Big Block Chevy Engines that I made and see if you can understand it. There is more of an explanation below the chart. For other engines you will use the firing order that matches your engine to create a similar chart. This chart is based upon "opposite" cylinders of your firing order. (see below)
    Intake Valve Adjustment: ENGINE OFF!
    ■with #1 cylinder Intake Valve at full valve lift .... Adjust #6 Intake Valve
    ■with #8 cylinder Intake Valve at full valve lift .... Adjust #5 Intake Valve
    ■with #4 cylinder Intake Valve at full valve lift .... Adjust #7 Intake Valve
    ■with #3 cylinder Intake Valve at full valve lift .... Adjust #2 Intake Valve
    ■with #6 cylinder Intake Valve at full valve lift .... Adjust #1 Intake Valve
    ■with #5 cylinder Intake Valve at full valve lift .... Adjust #8 Intake Valve
    ■with #7 cylinder Intake Valve at full valve lift .... Adjust #4 Intake Valve
    ■with #2 cylinder Intake Valve at full valve lift .... Adjust #3 Intake Valve
    Exhaust Valve Adjustment: ENGINE OFF!
    You will notice that this is the same procedure and sequence as the intake valves listed above. Only now you are adjusting ONLY the exhaust valves the same way.
    ■with #1 cylinder Exhaust Valve at full valve lift .... Adjust #6 Exhaust Valve
    ■with #8 cylinder Exhaust Valve at full valve lift .... Adjust #5 Exhaust Valve
    ■with #4 cylinder Exhaust Valve at full valve lift .... Adjust #7 Exhaust Valve
    ■with #3 cylinder Exhaust Valve at full valve lift .... Adjust #2 Exhaust Valve
    ■with #6 cylinder Exhaust Valve at full valve lift .... Adjust #1 Exhaust Valve
    ■with #5 cylinder Exhaust Valve at full valve lift .... Adjust #8 Exhaust Valve
    ■with #7 cylinder Exhaust Valve at full valve lift .... Adjust #4 Exhaust Valve
    ■with #2 cylinder Exhaust Valve at full valve lift .... Adjust #3 Exhaust Valve

  9. #9
    Member JUNIOR BUILDER
    Join Date
    Jun 2004
    Location
    lake luzerne n.y.
    Posts
    87
    Quote Originally Posted by fla1976
    This is how I adjust valves. The website has excellent info on valve adjustments but there is too much info to list here.

    http://www.centuryperformance.com/ad...h-spg-149.html



    Valve Adjustment Procedure - The Quick and Accurate Way:
    First, view this little chart below for Small and Big Block Chevy Engines that I made and see if you can understand it. There is more of an explanation below the chart. For other engines you will use the firing order that matches your engine to create a similar chart. This chart is based upon "opposite" cylinders of your firing order. (see below)
    Intake Valve Adjustment: ENGINE OFF!
    ■with #1 cylinder Intake Valve at full valve lift .... Adjust #6 Intake Valve
    ■with #8 cylinder Intake Valve at full valve lift .... Adjust #5 Intake Valve
    ■with #4 cylinder Intake Valve at full valve lift .... Adjust #7 Intake Valve
    ■with #3 cylinder Intake Valve at full valve lift .... Adjust #2 Intake Valve
    ■with #6 cylinder Intake Valve at full valve lift .... Adjust #1 Intake Valve
    ■with #5 cylinder Intake Valve at full valve lift .... Adjust #8 Intake Valve
    ■with #7 cylinder Intake Valve at full valve lift .... Adjust #4 Intake Valve
    ■with #2 cylinder Intake Valve at full valve lift .... Adjust #3 Intake Valve
    Exhaust Valve Adjustment: ENGINE OFF!
    You will notice that this is the same procedure and sequence as the intake valves listed above. Only now you are adjusting ONLY the exhaust valves the same way.
    ■with #1 cylinder Exhaust Valve at full valve lift .... Adjust #6 Exhaust Valve
    ■with #8 cylinder Exhaust Valve at full valve lift .... Adjust #5 Exhaust Valve
    ■with #4 cylinder Exhaust Valve at full valve lift .... Adjust #7 Exhaust Valve
    ■with #3 cylinder Exhaust Valve at full valve lift .... Adjust #2 Exhaust Valve
    ■with #6 cylinder Exhaust Valve at full valve lift .... Adjust #1 Exhaust Valve
    ■with #5 cylinder Exhaust Valve at full valve lift .... Adjust #8 Exhaust Valve
    ■with #7 cylinder Exhaust Valve at full valve lift .... Adjust #4 Exhaust Valve
    ■with #2 cylinder Exhaust Valve at full valve lift .... Adjust #3 Exhaust Valve
    Yes but this info needs to be adjusted for altered cams, 4-7 swap cams or 4-7-,2-3 swap cams.

    The easiest way I have been taught to adjust valves is from reher morrison. If you take one cylinder at a time, when the exhaust valve begins to open you adjust the intake valve, Rotate the motor and when the intake valve begins to close adjust the exhaust valve.
    I also found that when I set the lash cold i need to go back around once the motor warms up and adjust them again because it changes significantly. I always check them now when the motor is hot.

  10. #10
    Senior Member EXPERT BUILDER
    Join Date
    Sep 2003
    Posts
    259
    when the intake valve begins to close



    Its when the intake is ALMOST closed adjust the exhaust valve on that particular cylinder.


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Copyright © 2005-2016 RacingJunk.com All Rights Reserved.

Designated trademarks and brands are the property of their respective owners. Use of this Web site constitutes acceptance of the RacingJunk.com
Terms of Use, Classifieds Disclaimer, Privacy Policy, and Cookie Policy