Page 1 of 2 12 LastLast
Results 1 to 10 of 17

Thread: Lash adjustment

  1. #1
    Member MASTER JOURNEYMAN
    Join Date
    Feb 2008
    Posts
    45

    Lash adjustment

    Getting ready to set lash on my first solid roller the mfg. recommends .021 int. side .023 exh. side hot. Should i allow a couple thou extra clearance due to the fact my initial set-up is cold. I figure later i can do the math and calculate the expansion of the alum heads so i can do them cold.

  2. #2
    Senior Member RACING JUNKIE curtisreed's Avatar
    Join Date
    Feb 2004
    Location
    KIEFER, OK.
    Posts
    1,309
    You will pick up about .005-.006 after the motor heats up. If you need .021 hot set them at .015-.016 and .017-.018 cold.

    That is with iron block and aluminum heads.

    Curtis

  3. #3
    Member MASTER JOURNEYMAN
    Join Date
    Feb 2008
    Posts
    45
    Curtis: Thanks for the info, i'm surpised they expand that much but i will use your info for my starting point. Again Thank You.

  4. #4
    Senior Member EXPERT BUILDER
    Join Date
    Jan 2005
    Posts
    336
    my big chevy stuff requires .004 to .005 less clearance cold.most were fine with .004 tighter,but about 2 per side needed to be slightly tighter when checked hot

  5. #5
    Senior Member MASTER BUILDER
    Join Date
    Mar 2008
    Posts
    173

    valve lash

    i have sbc iron block and iron heads. i set my valve cold just the opposite. i set them looser and when they heat up they tighten (example) i set them cold around 26 to get about 22 when hot. is this correct chevy art

  6. #6
    Senior Member RACING JUNKIE
    Join Date
    Sep 2007
    Posts
    4,143
    Quote Originally Posted by doorracer
    You will pick up about .005-.006 after the motor heats up. If you need .021 hot set them at .015-.016 and .017-.018 cold.

    That is with iron block and aluminum heads.

    Curtis
    X2

    I have a Big Chevy with iron block/aluminum heads and mine opens up about .006 when it heats up. What I do is set them about .006 tight to get the thing started, then get it up to operating temp and check them and see how much they opened up.That way you know how much and then you can do the math and just set them cold every time. JUST MY OPINION

  7. #7
    Senior Member RACING JUNKIE curtisreed's Avatar
    Join Date
    Feb 2004
    Location
    KIEFER, OK.
    Posts
    1,309
    heshtesh, one other thing I would mention is the way I set the lash. If you are shooting for .020 setting, (arbitrary number), I use a .019 and .021 feeler guauge as a go and no-go. .019 goes easy and .021 will not go, gets you right on .020. I guess I have been a machinist to long to just set it with the size gauge I am shooting for.

    Curtis

  8. #8
    Senior Member DYNO OPERATOR
    Join Date
    Aug 2007
    Location
    Lost Creek, WV
    Posts
    533
    There was some discussion on this subject a little while ago. So the last time I adjust the valves on my motor, ( small blocl chevy, cast block & aluminum heads) I set them .006 tight cold. Warmed the engine up to 200 degrees, pulled the rocker covers and the lash was right on the money.

    TS1955

  9. #9
    Senior Member DYNO OPERATOR
    Join Date
    Feb 2009
    Posts
    510
    Quote Originally Posted by doorracer
    heshtesh, one other thing I would mention is the way I set the lash. If you are shooting for .020 setting, (arbitrary number), I use a .019 and .021 feeler guauge as a go and no-go. .019 goes easy and .021 will not go, gets you right on .020. I guess I have been a machinist to long to just set it with the size gauge I am shooting for.

    Curtis

    KD tools make s go-nogo feeler gauge. I have one. Pretty cool to get your lash adjusted "just right".

  10. #10
    Senior Member RACING JUNKIE TheRabbit's Avatar
    Join Date
    Jan 2007
    Location
    Augusta, Ga.
    Posts
    2,295
    Their will always be a debate over setting lash over hot vs cold. Hot is better, but the average racer doesn't do it fast enough to keep the temp steady. I've been through this so many times with my engine builder and this is his take on it. The lash is set and adjusted correctly during breakin once the motor is hot. Once I get it I check and see what feeler guage will fit. I don't care what size it is. Just get my feel for it. Noone can tell you .016 - .018 cold or .022 or .024 is perfect. Everybody has a different feel for .022. Some tight, some loose, some snug. .002 isn't going to make a difference, but they all need to be the same!! If you error do it on the tight side! What I'm trying to say is set them the same everytime YOURSELF. Smaller or lazy cams likes more lash, but even that isn't always 100% true. A good valve train SHOULD NOT MOVE. IF IT DOES SOMETHING IS WRONG!!! Take notes which ones you have to adjust and which way. If you have to keep getting tighter you probably have a seat problem. Bottom line is if you have to adjust the same ones next time look at everything really close!!


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Email us - Support@RacingJunk.com
Call us - 866.326.9227
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