Part 1. Preparation and safety
Objective
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection - such as rubber gloves and barrier cream
- Respiratory equipment - such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Follow the firing order when adjusting the valve lash.
Part 2: Step-by-step instruction
- Prepare to adjust valve lash
Just as you did for the Pre-Assembly check, for the Final Assembly of engines with hydraulic lifters, you need to adjust to zero lash so that all the slack is taken out. Then, tighten the nuts down another half-turn.
When the lifters are installed, every time the engine rotates, the protective lubricant is being slowly wiped off the cam lobes. However, If you follow the firing order of the engine, the camshaft only has to rotate one full turn to carry out the whole lash adjusting procedure.
- Find number one compression stroke position
As you rotate, look at the intake lifter or pushrod of the number one cylinder. The exhaust will open first and then the intake. As soon as the intake returns to its lowered position, stop rotating. The cylinder is now on its compression stroke and both lifters will be in their lowered positions.
If you have non-adjustable rockers, you can install both rocker nuts and tighten and torque them for the number one cylinder.
- Find zero lash point
For adjustable type rockers, spin the pushrod with your fingers as you tighten the rocker nut. It can be difficult to tell the exact point where all the slack is gone and the pushrod becomes a little harder to spin. While you're turning, feel for a slight difference in resistance to spinning the push rod. That should be the zero lash point where the pushrod is unable to move up and down at all. When you get close to zero lash, it helps to hold the wrench up a little bit, so that the socket is not sitting on top of the pivot ball.
- Set valve pre-load
When you are sure the valve assembly is at zero lash, align the wrench straight and give the nut exactly one more half turn. This pinches the plunger down in the hydraulic lifter to set the pre-load.
When the engine is running and oil fills up inside the lifters, the preload on the lifter keeps the valve train from making chattering noises.
When you add the extra half turn to a reused hydraulic lifter that already has oil in it, the valve may actually open slightly. This is normal. If you had a gauge installed, you would see that after a minute or two the pressure inside the lifter will bleed off and the valve will return to its closed position where it should be.
- Repeat process in firing order
The firing order will tell you which rocker to adjust next. On a V8 engine, whichever cylinder is next after the first will already have the intake lifter in the up position. Rotate the engine about a quarter turn and the intake lifter will return to its bottom position. Then adjust the rockers for that cylinder. Carry on through the firing order and, each time, the next cylinder will have the intake lifter in the up position.
When all of your rockers are adjusted, the camshaft will only have rotated once and there should be plenty of break-in lubrication left on the cam lobes.
