Month: August 2012

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Engine Rebuilding tips Adjusting Hydraulic Lifters

Adjusting Hydraulic Lifters for Proper PRE-Reload on your next engine rebuilding project more Tips for your Engine.

Since hydraulic lifters can compensate for thermal expansion of the engine, the adjustments can be made with the engine cold; hot adjustment is not necessary.

In order to adjust the reload the lifter must be properly located on the base circle or “Heel” of the lobe. At this position the valve is closed and there is no lift taking place.You will need to watch the movement of the valves to determine which lifter is properly positioned for adjusting.

1. Remove the engine valve covers, and pick a cylinder you are going to set the preload on.
2. Hand rotate the engine in its normal direction of rotation and watch the exhaust valve on that particular cylinder.When the exhaust valve begins to open, stop and adjust that cylinder’s intake rocker arm. (Why? Because when the exhaust valve is just beginning to open, the intake lifter will be on the base circle of the lobe, the correct position for adjusting the intake.)
3. Back off the intake rocker arm adjuster and remove any tension from the pushrod.Wait a minute or two for that hydraulic lifter to return to a neutral position. The spring inside the lifter will move the pushrod seat up against the retaining lock if you give it time to do so. (If you are installing brand new lifters they will be in the neutral position when they come in the box.)
4. Now spin the intake pushrod with your fingers while tightening down the rocker arm.When you feel a slight resistance to the turning of the pushrod, you are at “Zero Lash”. Turn the adjusting nut down one half to one full turn from that point. Lock the adjuster into position. The intake is now adjusted properly.
5. Continue to hand turn the engine, watching that same intake. It will go to full open and then begin to close.When it is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. (Again, when we see the intake almost closed, we are sure that exhaust lifter is on the base circle of the lobe.) Loosen the exhaust rocker arm and follow the same procedure described before in steps 3 and 4 to adjust this rocker arm.
6. Both valves on this cylinder are now adjusted, and you can move on to your next cylinder and follow the same procedure again.
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Most Important Factors for Choosing Valve Springs

The three most common factors that should be considered are installed height, camshaft type, and cylinder head valve spring pocket dimensions. Each consideration is equally critical to choosing the correct valve spring for your application.

 To begin, your installed height should always be measured. This is important because the height at which a valve spring is installed can dramatically increase or decrease its rated coil bind clearance and opened/closed pressures. As this can lead to valve spring or camshaft failure, it is vital that you choose the correct spring for the installed height that your cylinder heads can accommodate.

The next consideration is camshaft type. In short, your valve spring pressure rating must be appropriate to the type of camshaft that you are using. Failure to run the correct pressure for the cam type will almost certainly result in engine damage. See the table below for general spring pressure guidelines based on cam type.

Finally note the physical diameter of the spring. Cylinder heads have pockets that can only accept certain diameter valve springs without machine work. To help circumvent the need for machine work, some manufacturers offer a wide selection of valve springs, as well as valve spring locators and shim kits to simplify the installation process.

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Valve Lash can Help Tune the Engine !

The engine only responds to the actual movement of the valves. Since the valve cannot move until all the running clearance (valve lash) has been taken up, the amount of valve lash you use affects the engine’s performance.

If you decrease the amount of (hot) valve lash, for example, the valve will open slightly sooner, lift higher and close later. This makes the camshaft look bigger to the engine, because of a slight increase of actual running duration and lift. If you increase the amount of (hot) lash the opposite occurs. The valve will open later, lift less, and close sooner.

This shows the engine a smaller cam with slightly less actual running duration and lift. You can use this method on a trial basis to see what the engine responds to and keep the setting that works the best. Just remember, the more lash you run, the noisier the valve train will be. If the clearance is excessive it can be harsh on the other valve train components.

Therefore, for prolonged running of the engine Mayor`s does not recommend increasing the amount of hot lash by more than +.004″ from the recommended setting. And they do not recommend decreasing the hot lash by more than -.008″.