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Thread: need help

  1. #1

    need help

    whats the best technic to set valve lash on a sbc thanks.

  2. #2
    Senior Member EXPERT BUILDER
    Join Date
    Aug 2007
    Location
    Orient, OH
    Posts
    384
    Here is the way that I do it.

    Go cylinder by cylinder and set both valves on each cylinder before moving to the next. Watch the exhaust valve and bump the motor over until the exhaust valve JUST begins to open - set the INTAKE valve of that cylinder. Next watch the intake valve you just set and bump the motor over until that intake valve opens all the way and then begins to close - set the EXHAUST valve on that cylinder. Do this for each cylinder and you're done.
    Josh VanHorne

    1964 Chevy Nova
    Worlds quickest and fastest tow truck. (9.92 @ 137)

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  3. #3
    Senior Member DYNO OPERATOR
    Join Date
    Apr 2008
    Posts
    504
    I do all of mine this way. First I start by 1/4 marking my harmonic balancer so that I have a line marked on it every 90 degrees. The marks will line up with your pointer when each cyl is at exact top dead center. This method eliminates error and improper lash adjustments that you can get in any position other than top dead center or the heal on larger cams.
    You go right thru the firing order 18736542 if you have a 4/7 swap cam or 18436572 beginning with cyl # 1 on compression stroke at top dead center, 0 on the pointer, doing both intake and exhaust valves on each cyl at the same time, every 90 deg is the next in the firing order. Most cam specs require the adjustment to be made at a temperature pre determined. If you do not have recommendation on temp, then do the lash at 140 deg F so that you can check the lash at that same temp each time to give relevant check's of lash adjustment. If you have aluminum heads the adjustment cold, for initial fire up will need to be set about .006 less that the spec on the card which reflects hot lash always. I hope this gives you something to run with. Simpler and accurate is always repeatable and correct.
    PS on my stuff I don't use the temp gauge in the car, I use an infared hand held one that I use for checking starting line temps with. I shoot the neck where coolant comes out and do the lash while the electric water pump is on to give the most accurate temp setting with the fan off. The circulation helps prevent the aluminum from cooling unevenly from removing the valve covers etc. It makes a difference on all aluminum engines and aluminum heads too. You do not have to circulate coolant in yours to get a good lash, but if you can, you should.
    Long PS huh :lol:


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