Setting or changing valve lash for the first time can seem like a difficult operation, but it is incredibly necessary to get the maximum performance out of your engine, even though it is sometimes disregarded. When it comes to valve lash, it is the mechanical clearance that exists between a rocker arm’s tip and the tip of a valve stem. The duration of the lift will be reduced if there is too much valve clearance present, which will result in excessive wear on the valvetrain and increased noise in the engine. When the valves are too tight, they can hang open, resulting in poor performance and excessive wear on the valvetrain components. When it comes to setting valve lash, there are various options to choose from. However, if you follow the engine’s firing order, you will only need to rotate the cam one full turn (2 crankshaft rotations) to accomplish this procedure.
How to Set SBC Valve Lash
Make sure the engine is completely cold before starting it. To double-check the engine’s rotation, you can place timing tape on the balancer or very precisely measure and mark the balancer every 90 degrees with a pencil to double-check its rotation.
Before you begin, make sure to apply a substantial amount of high-quality assembly lubrication to all of the contact surfaces, such as Isky Rev Lube or Red Line oil.
Turn your engine to the top dead center compression stroke on the number one cylinder with the valve covers removed and spark plugs removed. This can be accomplished by keeping an eye on the movement of the lifters or rocker arms – the exhaust will open first, followed by the intake. The compression stroke begins as soon as the intake valve returns to its fully closed position after being partially opened.
You may now adjust the valve lash on both the intake and the exhaust valves at the same time. The appropriate tuning of the majority of hydraulic lift camshafts will necessitate zero lashes. Regardless of whether you have stamped steel rockers or roller tip rockers, the technique will be the same.
To obtain zero lashes, tighten down the rocker while spinning the pushrod in your fingers, doing so until you notice a tiny resistance when spinning the pushrod in your fingers (this is zero lash). In addition, there should be no lateral movement in the pushrod any longer as well.
When you’re sure you’ve reached zero lash, tighten the rocker another 1/2 turn to ensure that the lifter, pushrod, and rocker’s arm are all loaded to their maximum capacity.
As soon as you move to the second cylinder in the firing order, the intake valve should have already been opened. Repeat the technique by rotating the engine another 90 degrees or 1/4 turn clockwise while keeping an eye on the lifters to ensure that you are on the base circle of the camshaft lobe.
As you progress through the firing sequence, the intake valves on each cylinder should be open at all times. To tighten each rocker, simply follow the procedure on each cylinder and be consistent throughout the process.