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Thread: Valve Lash Adjustment Procedures

  1. #1
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    Valve Lash Adjustment Procedures

    Valve Lash Adjustment Procedures
    by Brian Tooley
    There are numerous ways to lash valves in an engine. We will discuss only what we feel are the best ways. The method that we prefer will work on any camshaft type, the only difference is the amount of lash that will be used. We use the "firing order method" of lashing valves. We can lash the valves on an engine stand and never have to readjust them once run in the car.
    Step #1 Find top dead center for piston #1
    A lot of people think that if the timing pointer is on the balancer mark that this is TDC #1. This is not necessarily true, it can be TDC #6. This is because there are 720 degrees crankshaft rotation in one complete firing sequence. There are two ways to find TDC #1. First is by pulling the #1 spark plug, holding your finger over the hole and turning the crankshaft until it tries to blow your finger away, then once the timing mark comes up this will be TDC #1. The other method requires the valve cover or intake to be off. You can look at the lifters or rockers of #1 and #6 cylinders. When #1 is at TDC, #6 has both valves open slighty. If you move the balancer timing mark to each side of the timing pointer, you should see both lifters or rockers of #6 moving up and down and #1 should remain stationary. If it is vice versa then you are on TDC #6 and need to move the crankshaft 360 degrees or one full turn.
    Step #2 Adjust the the lash of #1 cylinder
    This is where you have to determine the lash you will use. If it is a solid or solid roller application then the lash will generally be between .016" and .030". For hydraulic and hydraulic roller applications we prefer to go 1/4 turn more than "0". We turn the poly lock while moving the rocker arm up and down on the valve. Once all play is taken out go 1/4 turn more and then lock down the inner set screw. Another thing you can do at this point is go just shy of 1/4 turn, lock down the inner set screw and then put the wrench on the poly lock and turn it as far as you can, within reason. This helps lock down the poly lock to keep it from backing off.
    Step #3 Turn the crankshaft 90 degrees
    Turn the crankshaft 90 degrees or 1/4 turn to the next cylinder in the firing order. Repeat Step #2. The next one in the firing order is obviously dependent on the engine you have. All V8 Chevys (small block and big block) are 1-8-4-3-6-5-7-2. 302HO and 351W are 1-3-7-2-6-5-4-8. Non-HO 302 and 289 are 1-5-4-2-6-3-7-8.
    Step #4 Keep going
    Keep turning the crank in 90 degree increments and lashing the valves for that cylinder until all 8 cylinders have been adjusted. At that point you should have to turn the crank one more 90 degree turn and you will be back on #1 TDC.
    For you serious race car guys with gross duration figures in the 320 plus region you can use the firing order sequence but instead of adjusting the #1 valves at TDC #1 adjust the previous intake rocker and the next exhaust rocker. This ensures that the lifter is on the absolute base circle of the camshaft.
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  2. #2
    "I'm PlanZ Bitch!" Pit Crew Member plan Z is your basic, average member!
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    ive set mine a few times with the car off and keep on reverting back to the engine running method. i guess its whatever works for you

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