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Valve Adjustment, Flat Tappet Cam Break-In - Hydraulic Lifters

Although hydraulic lifters shouldn't require any adjustments during normal service, it is important to check the lifter pre-load when lifters are installed. Adjust as necessary. Lifter pre-load is the distance between the retaining snap ring and the push rod seat in the lifter when the lifter is on the heel of the cam lobe with the valve closed. A number of things can affect lifter pre-load:

        1.Resurfacing the heads and/or block deck

        2.Changes in camshaft diameter

        3.Changes in push rod length

        4.Changes in valve length

        5.Changes in rocker arm length or geometry

        6.Changes in head gasket thickness

        7.Changes in lifter height

        8.Valve job

        9.Different rocker arm stands or shafts

Be sure and check the valve geometry and use either longer or shorter push rods to correct the geometry.
In some cases on shaft systems a shim under the rocker shaft may be required to maintain correct geometry.

When installing new hydraulic lifters, follow the proper OEM procedures for checking and
adjusting lifter pre-load.

Initial settings on Hydraulic lifters-PRELOAD

Presuming that your using an aftermarket QUALITY set of hydraulic lifters this procedure should be right for your application.  It is your responsibility to assure that this tutorial applies to your specific application.

This procedure is what we use for a Racer Brown Cam and Lifter set with adjustable rocker arms.
   
    Install the push rods and rocker shafts, backing the adjusters all the way out  to be sure you don't jam a valve.

    While priming the engine with a drill motor and priming tool we rotate the engine 360* X 2 to rotate the cam.
    This will bring oil to the lifters and support the push rod seat during adjustment.

    With the intake manifold off you can see the cam lobes and easily determine when the lifter is on the backside of the cam and the valve is in the closed position.

    This part requires the gentle touch of a brain surgeon, once you have determined that the lifter is on the backside or heel of the cam start tightening the adjuster on the rocker arm, gently take up the slack while rotating and moving the pushrod up and down until the rocker arm forces the pushrod to JUST TOUCH the cup in the lifter.  The pushrod should rotate in your fingers easily with zero up and down movement.  

    Don't make the mistake of forcing the push rod up and down as the hydraulic lifter cup is supported by a tiny spring and you can collapse the lifter if you push hard enough and force the push rod to the bottom of the main body of the lifter.  This will give you excessive valve train load and probably kill your cam, bend a pushrod or ruin a good lifter or a variety of other catastrophic results that we can discuss at some other time...bottom line, be gentle and don't over tighten.  

    After you set the valve you should be able to force the rocker arm down on the push rod and it will give slightly....the amount of force is going to depend on how much oil pressure you pumped up into the lifter during the priming procedure and how much it held.  

    Once you rotate the cam to the next valve you may have some slack in the lifter as the spring pressure will try and bleed off the oil in the  lifter and bottom out the push rod, this of course is normal.

    Once you have determined zero lash tighten the rocker arm adjuster bolt 1/2 turn, this is the preload we use, check with your cam and or lifter manufacturer to confirm preload settings.

    Now on to the other 15, try to rotate the engine as little as possible, go in both directions to minimize rotation of the cam after your all done. Use a break-in oil of your choice and pour some over the cam lobes,  install the manifold and try and fire the engine within 24 hours.  We usually leave the lifter adjustment until the engine ready to install and we're ready to fire it off.


Initial Start-Up

It is important that the engine starts immediately.
Prolonged cranking may damage the camshaft, lifters and/or followers.
Before starting the engine, top off the coolant level and make sure the ignition timing is properly set. After starting the engine, DO NOT let it idle. It is essential to run the engine at 1800-2200 RPM for at least 20 minutes.
Because the camshaft and lifters are primarily lubricated by the splash of oil from the crankshaft, any RPM below 1,800 may result in insufficient lubrication and may cause cam lobe failure.
The high RPM also allows the lifters to rotate quicker and seat properly to the camshaft during this critical break-in procedure. During the first 20 minutes, carefully monitor oil pressure and temperature, if any problems arise, shut down the engine immediately.

Remember, DO NOT allow the engine to idle.

Typically, whenever a bigger valve spring is used, greater precision is required to maintain reliability. Cleanliness, alignment, clearances, journal surface finishes and lubrication must all be controlled more closely.

Here are some tips to help maximize performance and longevity when using aluminum alloy camshaft bearings.

There’s many things that can cause a cam to go flat here are a few of the most common.

         Not following the camshafts manufactures instructions to the letter.

         Not using enough break-in lube
         
   
        At least 15 minutes of engine run in at a minimum of 2000 rpm.

        Improper valve adjustment during break-in

        Valve train interference: check retainer to guide, rocker arm to retainer, rocker arm slot to stud, valve to piston, valve spring coil binding or  weak springs allowing lifter to bounce on lobe and a sticky valve in the guide from incorrect clearances. Most Common... Too much spring pressure.

        Not using a break-in oil

        Not priming the oil system before startup. Using a priming shaft and drill you should prime until you get oil up to the rockers.

        Having to crank engine over for say 30 seconds or more before it fires or if your not able to keep running at the required rpm immediately after it fires, cam failure is very possible.

        Dirt or blast media left in engine.

        Rule of thumb….whatever Oil pressure you get with the drill during priming is what you’ll have at idle, if you can only crank 20# with the drill it is likely that’s all you’ll have at idle and something may be wrong.

This is only a guide and a few tips to help with break-in and nothing here guaranty's that your break-in will be successful.  The only way that we know of to guaranty a successful break-in with any flat tappet Hydraulic or Solid lifter cam is to use a ceramic tipped lifter by SM Machine.  These require NO Break-in and NO special oils, however even with Ceramic type lifters Manufacturers recommendations MUST be followed to the letter.


 

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