Valve Adjustment, 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 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 you’re 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 360^o
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 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 but we're after 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 or 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.  

Once you rotate the cam to the next valve you may not have much 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 pour a quart of Power Punch or TX-7 over the cam,  install the manifold and try and fire the engine within 24 hours.  We usually leave the lifter adjustment until the engine is in the car and we're ready to fire it off.

IMPORTANT UPDATE:
We highly recommend that use a pint of GM EOS, engine oil supplement to ensure a good break-in, we will not sell a cam without a pint of EOS and we insist that it be used for break-in. No exceptions

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, 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 aluminium alloy camshaft bearings.

Sufficient clearance is necessary in the initial installation. These stronger bearings will not wear in rapidly to make their own clearance like softer materials. Minimum clearance should be .002" for stock engines and .003" for high performance.
Optimum clearance range for high performance applications is .003" to .004". Because of the stack up of tolerances on the block, shaft and bearing it is impossible to control clearance to this range in the manufacture of the bearing alone.

Clearances must be measured at installation.

Honing the ID's of cam bearings to increase clearance is not recommended because hone grit may become embedded in bearing surfaces which will cause shaft wear. Bearing ID's may be reamed, but the most practical means is to adjust camshaft journal diameters by grinding. Even if not ground to provide additional clearance, camshaft bearing journals should be polished to a surface finish of 10 micro-inches RA or better with the camshaft rotating in the same direction it will rotate in the engine.

Like clearance, alignment is also extremely important especially for high performance applications.
Any block that has needed to have its main bearing bore alignment corrected due to distortion is likely to have experienced cam bearing bore distortion as well. Adequate clearance will help compensate for minor misalignment of less than .001". Special cam bearing sets with oversize outside diameters are available for most engines to allow align boring the camshaft bearing housing bores in these engines.

Tri-metal bearings are priced higher than the aluminium alloy bearings but offer the added advantage of a thin electroplated babbitt overlay for improved bearing surface properties in combination with high strength.

It should be noted here that modern bearing and cam manufacturing usually eliminates the need for any of this unless the cam feels loose or excessively tight once installed clearance of the cam bearings is not necessary.  I can't remember that last time we had a tight or loose cam.

Camshaft Break-In Procedures
   
Coat the camshaft lobes & distributor gear with a generous amount of cam lube, I like the Torco or Redline or as supplied by the cam manufacturer.
    
Apply the Cam Lube lubricant only to the lifter contact faces - not the bores.

Prime the oiling system using new oil and filter.  Rotate the engine 360* slowly by hand to circulate oil to both heads.
     
Use only oils that meet or exceed the latest API ratings.
     
Do not use non-detergent oils, they do not have the anti-scuff additives found in modern detergent oils.

I always add a quart of Power Punch or TX-7 to ensure lubrication.

Always use EOS
    
Start the engine and increase the RPM's to 2000-2200. Operate the engine for 15-20 minutes at this speed. The higher speeds increase splash lubrication and decrease nose loading.
    
Avoid excessive cranking, no start? Find out why!
    
The break-in procedure must commence as soon as the engine has oil pressure. If the engine fails to start within 15-30 seconds, it is recommended to re-apply the EP lubricant to the lobes.

There are 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
         
Not using EOS
     
Not allowing At least 15 minutes of engine run in at a minimum of 2000 rpm.

Improper valve adjustment during break-in: too tight, should only be 1/4 to 1/2 turn past 0 lash or 1/4 to 1/2 of lifter plunger travel.

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 spring allowing lifter to bounce on lobe and a sticky valve in guide.

Not using fresh high quality oil with a SJ or CD designation.

Not priming the oil system before start-up. Using a priming shaft and drill you should prime until you get oil up to the rockers, a pain but very good insurance.

Having to crank engine over for say 20 seconds or more before it fires, or if you’re 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 20psi with the drill it is likely that’s all you’ll have at idle and something is defiantly wrong.


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