breaking in a cam


Staff member
Cam Break-in Procedure
you might want to read thru this

preventing cam & lifter break-in failures

viewtopic.php?f=62&t=1515 ... number=EOS ... CEDURE.pdf


read this ... reakin.pdf


it should be rather obvious that theres options, cam failures are usually the result of incorrect CLEARANCES or too much SPRING PRESSURE or LACK of ADEQUATE LUBRICATION,USE DECENT MOLY CAM LUBE, and decent quality oil, adding MAGNETS to trap metallic CRUD HELPS, be sure to change your oil filter and oil after the first 3-4 hours or 100 miles as theres bound to be crud and assembly lube trapped in the oil and filter

OK step one you NEVER start an engine with a new cam untill youve verified ALL clearances and valve train geometry are correct!
and you have pre-lubed the engine while slowly manually rotating the crank untill all pushrods show oil flow,at the rockers and the gauge shows a minimum of 10 psi

• Have a high quality service manual available, such as the factory service manual, or the vehicle specific manuals published by Chiltons, Motors, or Haynes. You will need these for the basic information regarding engine disassemble and reassemble along with the torque settings for the various fasteners.

• Read and understand the manual completely, along with these instructions before you begin working. We highly recommend you also have the assistance of a knowledgeable friend to assist you, especially during the initial fire-up and break-in period.

In addition to the normal installation procedure, installing a performance camshaft requires you to check for several extra items to insure long life and optimum performance.

• New Lifters Are A Must- There is no such thing as a good used lifter! Any flat faced lifter establishes a wear pattern almost immediately with the cam lobe it is riding on and cannot be used on any other cam lobe, let alone a different cam. Should you have a need to disassemble the engine, make sure you keep the lifters in order so they go back on to the exact same lobes.

• Valve Spring Pressure and Travel- We highly recommend purchasing the matching valve springs recommended in our catalog. This insures you will have the proper pressures, both closed and open, and sufficient travel to get the maximum rpm, performance and life from your new cam.

• Piston to Valve Clearance- While many performance cams will work just fine with stock pistons, there are many factors that effect your engine and the clearance available. Things such as factory tolerances, normal machine work such as head and block surfacing, aftermarket components such as cylinder heads, higher ratio rocker arms, etc. all effect your engines ability to handle a performance camshaft.

• Valve Train Interference- In addition to valve spring travel and piston-to-valve clearance, a commonly overlooked area is that of retainer to seal clearance. The other common area of interference is rocker arm to stud clearance along with rocker arm travel. The best way to check these is by physically opening both a intake and an exhaust valve on each cylinder head to the gross lift of the cam plus and additional .030". It is easiest to do this by pressing down on the rocker arm with one of the many tools available. Do not simply rotate the engine to the maximum lift point for a given valve. This does not work when engines are hydraulic lifter equipped, or even allow any margin of safety when you are using a mechanical lifter cam.

• Valve Adjustment- The easiest way to insure proper adjustment is to adjust the rocker arms as you install them, one cylinder at a time. Adjust the intake valve as the exhaust valve is just starting to open and adjust the exhaust valve when the intake valve is almost closed. It is simplest to do this with the intake manifold off and watching the lifter’s movement.

• Hydraulic Lifter Valve Adjustment- All engines, regardless of manufacture, require correct valve adjustment. Some engines, such as Chevrolet V-8’s, are equipped with stud mounted rocker arms can easily be adjusted to compensate for changes incurred during engine assembly. Never just torque the rocker arm into place and assume that the lifter preload will automatically be correct. Various engine manufacturers use multiple length pushrods, shims, and spacers to compensate for changes in preload. Hydraulic lifters cannot compensate for all changes. Ideal lifter preload is .020" to .080". Do not attempt to fill the lifters full of oil prior to installation. They will fill automatically once started and manually filling them makes adjusting the preload a difficult task.

• Mechanical Lifter Valve Adjustment- Adjusting mechanical lifters should be done the same way as outlined above, one valve at a time. For an initial setting, we recommend .003" to .005" than listed on the cam’s specification card. Once broken in and with the engine fully warmed up, re set the rocker arms to the cam’s specification sheet.

• Installation Lubricants- All flat faced (non-roller) camshafts require the use of high pressure lubricant supplied with your Erson cam on the bottom of the lifters, the lobes of the cam and on the distributor drive gear. Do not use this lube on the tips of the pushrods, the sides of the lifters or on the rocker arms. Use a quality oil when installing roller tappets.


• Fill All of the Engine’s Fluids- Using a minimum of a SAE API SD, SE or better fresh clean mineral based oil, fill the engine to the proper level. Do not use synthetic oil during break-in. Fill the coolant system and follow the instructions on purging air from the system. With carburetor equipped engines, fill the carburetor to insure fuel is available immediately. Make sure that the ignition timing is properly set to insure immediate starting, without excess cranking of the engine.

• Pre-Lube the Engine- Using a oil pump priming tool such as those available from Mallory, spin the engine’s oil pump until you see pressure on the gauge or have oil at the rocker arms. Do not attempt to prime the engine using the starter motor!

• Proper Ventilation- Make sure that you do not start the engine without good airflow. That means have the overhead garage door open and the exhaust vented to the outside. If you have any doubts about sufficient airflow to the engine, push the car out of the garage to make sure the radiator can draw in plenty of air. Having a fan to blow fresh air through the garage is a plus.

• Exhaust System- If at all possible, start the car with a muffled exhaust system hooked up and operational. It makes it much easier to hear what is going on.

• Resist the Urge- Take a minute before you try to start the engine for the first time and double check that you are ready to go. Don’t take any short cuts or leave parts such as fan shrouds, air cleaner, wire looms, etc. off. Clean up the are around and especially under your vehicle. Pick up your tools and wipe up the floor so you can easily spot even a minor leak.

• Be Prepared- Have extra coolant or a hose handy, clean rags, tools for tightening clamps, connections, etc. just in case. They need to be in place to make sure you have an uneventful break-in of the camshaft.


• Have a Helper- Now is the time for a helper. They can check the coolant level, check for oil and fluid leaks, and proper operation of underhood accessories. Air pockets in the coolant system are common so make sure the recovery bottle is checked and filled as necessary. You cannot count on the temperature gauge. Temperature gauges are only accurate if the sensor is submerged in coolant and will not give an accurate reading if in an air pocket.

• Do Not Idle the Engine- As soon as the engine starts, raise the rpm to 2,000 rpm. You should also constantly vary the RPM between 2,000 and 3,000 RPM for the first 20 minutes. This is the only way to insure proper lubrication during this critical period since the camshaft to lifter contact area relies almost exclusively on oil splash from the crank and connecting rods. Make sure that you run the engine for a full 20 minutes using this procedure. It will seem like forever, but it is one of the most important steps to insure long, dependable performance.

Once Break-in is Complete- Drain and replace the engine oil and filter with new, fresh oil and a new filter. Recheck for any fluid leaks and check all fluid levels. If you installed a mechanical lifter style camshaft, flat faced or roller style, the valve adjustment should be rechecked at this time with the engine fully warmed up. Hydraulic lifter equipped engines should not require any readjustment.

Proper maintenance is important for any vehicle. Frequent oil changes, with a new filter is one of the easiest ways to insure your vehicle will deliver the performance you want for many long happy miles.


MARVEL MYSTERY OIL is a good high detregent oil designed to aid valve train and rings ETC. cleaning, I almost always add about 10% marvel mstery oil to my engines, but if your running flat tappet lifters Id point out that many current oils are designed for roller lifter engines so Id sellect an oil thats designed for the older design with the higher zinc content, and adding a can of E.O.S. to the oil and moly assembly lube on the lifters and cam, sure won,t hurt on that first break in, if your breaking in the engine in your driveway, have a running hose and a fan handy, water running thru the radiators cooling fins and a fan blowing air helps prevent over heating, have a timing light and USE IT, check your fluid levels and watch your gauges

Print this page out and check off boxes below (in the printed copy) when each step is completed.
Step Box
1) Safety first! If the car is on the ground, be sure the emergency brake is set, the wheels are chocked, and the transmission cannot fall into gear. Next verify that all hoses are tight and that both the radiator and radiator over flow jar/tank are full and have been filled with the proper anti-freeze and water mix.
2) Before starting your engine for the first time, add one pint of engine oil supplement ( EOS¹) to the crankcase oil and then check the oil level. Once this has been done, prime the oil system with an oil pump primer tool. Make sure number 1 cylinder is on TDC compression stroke, and install the distributor.
3) Adjust the distributor timing roughly by hand for a quick start up and smoothest idle possible.
4) When the engine first starts, verify that the engine rpm is at a safe level and that the timing is set near or at 30° before top dead center (BTDC). Run the engine speed between 1,500 and 2,500 RPM’s, varying the engine speed up and down with-in this range, to prevent overheating of the exhaust valves and the exhaust system. This should be done with no-load on the engine and for the first 30 minutes of operation.
5) After the first 30 minutes of the engine running, set the ignition timing according to the timing specifications. Now would be a good time to check thoroughly for leaks.
6) Adjust the carburetor settings, if necessary.
7) Drive the vehicle with varying speeds and loads on the engine for the first 30 miles. Be sure not to use a lot of throttle or high RPM.
8) Run five or six medium-throttle accelerations to about 3,800 RPM (55 to 60 MPH), then letting off in gear and coasting back down to 20 MPH.
9) Run a couple hard-throttle accelerations up to about 3,800 RPM (55 to 60 MPH), then letting off in gear and coasting back down to 20 MPH.
10) Change the oil and filter with recommended oil (10w30SG in most cases) and filter.
11) Drive the next 500 miles normally, without high RPM’s (below 3,800 RPM), hard use, or extended periods of high loading.
12) Change oil and filter again.
13) Your engine is now ready for many happy cruising miles!
Note¹: EOS P/N 1052367 can be used any time during the life of the engine.
Technical Note: This procedure has been corrected and improved from the original GMPP procedure by GILBERT CHEVROLET.

sitting with no air other than the fan moving air thru the radiator is bound to run a bit hotter than on the road, anything under 220F is normal /expected under those conditions.
I run a water hose thru the radiators cooling fins when testing under those conditions., on the street it should run fairly consistantlly in the 180F-190F range with a 180F T-stat.
in many cases an ADDITIONAL TAURUS electric fan from a salvage yard can be installed on the other side of the radiator to run off a dash switch or sensor that will provide additional cooling when needed.(price varies but its usually very reasonable from salvage yards) ... 1218835261


190F-210F is ABOUT NORMAL,for driving temps, and nothing to worry about, adding a seperately mounted TRANSMISSION COOLER if you have an auto trans is usually worth a 10-15 degree drop in the coolant temp,MINIMUM, if the current trans fluids cooled in the lower radiator, adding an 8 qt baffled oil pan is usually good for an additional 7F-10F degrees reduction in oil temp alone
A great deal of the heat is transfered to the oil and trans fluids long before the radiator and coolant sees it,routing the hot trans fluid to an aux cooler and adding a high capacity oil pan significantly reduces the heat the radiator needs to transfer from the coolant to the air flow thru it. ... toview=sku


Staff member ... toview=sku


you use a CRANK SOCKET to index the crank so the lower crank gear is at 12 oclock and the cam gear is at 6 oclock, and don,t for get to spin the engine one full revolution so the cam and crank gear are at 12 oclock before dropping in the distributor so the rotar points at the #1 cylinder or it will be 180 degrees out.
its false economy to do things cheaply if its very likely to result in less than ideal performance or problems with relieability.
the cam and crank gear are a matched set, and reuse of the old crank gear is NOT advised!
theres several totally differant types of chains and the gears and clearances are NOT always ,interchangeable ,... use of the wrong gear CAN cause excessive wear.
CLOYES makes TRUE ROLLER SETS that last longer and stretch less than the cheap imported link belt chains, that sell for $20 in the auto parts stores, its not un-common for the cheap sets to have the index off several degrees, and if you don,t degree in the cam its not un-common to have an engine run at less than its potential with the cam timing being off several degrees


its a good idea to mix some crane cams (MOLY) assembly lube and some marvel mystery oil in a tinfoil pan and soak the timing set in the mix for a few minutes before installing them, coating the surfaces tends to lower the tendency to wear as the moly forms a chemical layer that penetrates into the metals surface and protects it.


Staff member
ITS HIGHLY RECOMMENDED that you pre-prime the oil sysyem filter and oil passages on a new engine while you rotate it slowly by hand untill all the pushrods are flowing oil to the rockers.

Big Block Chevrolets have an oil-priming idiosyncrasy. When priming a Big Block Chevy with a drill motor and
priming tool, it is often necessary to prime for as much as 20 minutes (while rotating the engine) to get oil to all
of the lifters and rockers. It is advisable to prime these engines with the valve covers removed so you can
check to see oil coming out of all of the rocker arms before firing the engine. This last step is advisable on all
engines, but particularly on Big Block Chevrolets"


this type above is nearly WORTHLESS

this type bellow works just fine


SBCprimer.jpg ... toview=sku
they are dirt cheap or you can make one from and old distributor

be sure you turn the engine over at least two full turns while applying pressure to and lubing the oil passages to get full access to all the lifters,rockers,bearings etc.

"Why is the first one worthless?"

LOOK CLOSELY, the top primer has no collar to keep the drive shaft centered over the pump so it can slightly mis-align and bind, Ive seen them bend the pump drive if guys get them mis-aligned and just throw a high torque 1/2 drill on and spin them without checking, the lower primer has an alignment collar that tends to keep things from breaking,,yes both have the alignment collar for the manifold but only the botom one has the lower block support and alignment sleeve that forms the lower oil passage wall, and the drive collar that assure the oil pump drive itself is lined up correctly,keep in mind,the bottom of the stock distributor forms one wall of the main oil passage to one side of the engine, without that passage wall in place you get no oil pressure to one side and darn little to the other due to the HUGE leak the missing oil passage wall presents, the lower distrib is temporarily replaced with that extra aluminum on the lower primer to simulate the correct oil passage config....THATS WHY!

you MUST rotate the engine thru two complete revolutions (720 DEGREES)MINIMUM, and SEVERAL TIMES THATMANY TIMES IS ADVISED before every oil passage in every part is fully seeing the oil flow from the pump! that one lifter/pushrod may be in the part of the 720 degree cycle where little or no oil supply feeds it, try rotateing the engine bye hand with a breaker bar slowly, 720 degrees while a buddy applies full oil pressure with the drill on the oil pump primer tool, before worrying about it!a rod driving the oil pump may never build sufficient oil pressure to get oil to the rocker arms, because the distributor shaft forms part of the wall of the oil feed gallery, an oil pump primer tool must look like this, haveing the lower distributor houseing to seal the passage so that pressure can build through the whole system
putting a load on the rings and bearings with no oil flow or oil pressure to replace the assembly lube thats most likely being forced off those surfaces durring those first few seconds, and yes for a short time,yes you can do it that way but there is less stress on the engine doing it CORRECTLY by pre-filling all the oil passages and oil filter with oil and getting oil pressure to the bearings the instant the engine starts turning! theres lots of things that you can GET AWAY WITH,WITHOUT OBVIOUS DAMMAGE, but doing things CORRECTLY in most cases is by far the better plan,look Im not saying you CAN,T just hit the starter and spin the engine with the coil wire removed till you read oil pressure,BUT, I am saying that there are valid reasons for doing it correctly (PRE LUBE,& prefill the lube passages) that might not show up instantly but do show up under long term evaluation of the results«


The Grumpy Grease Monkey mechanical engineer.
Staff member
I see Lunati and Comp want you to remove the inner valve springs when breaking in a flat tappet.
How important is that and do all of you do that?

wolfplace said:
Depends primarily on your valve spring load rate open pressures
If I had to give a number it would be anything over 300 open I would recommend doing it if a dual & if a single use a set of softer springs
I would prefer something in the ±250 open range or even a bit less if you decide to do this


With today's flat tappet engines, and the new oils that have been designed almost exclusively for roller tappets,
proper break in is super critical. and it would be very much to your advantage to add an additive designed to reduce flat tappet cam wear issues.
removing the inner valve spring to reduce the pressure on the cam/lifter wear and load rates during initial cam break-in would be a good way to reduce the chance of having a cam lobe or lifter fail, during the break-in process ,if you have dual valve springs


Moly exists as microscopic hexagonal crystal platelets Several molecules make up one of these platelets. A single molecule of Moly contains two sulfur atoms and one molybdenum atom. Moly platelets are attracted to metal surfaces. This attraction and the force of moving surfaces in contact, rubbing across one another provide the necessary thermochemical reaction necessary for Moly to form an overlapping protective coating like armor on the rifle bore surface, This protective armor coating has a number of properties that are very beneficial for your rifles bore surface
moly is a bit like graphite, in that it appears to be a super fine powder suspended in a solvent carrier, that evaporates over time, put some between finger tips and rub, youll get the idea.. it spreads. like anti seize paste, and yeah it can be cleaned off hands with soapy hot water, but it gets into metal surfaces and its very dificult to remove (thats the idea)


The Moly platelets that make up the protective layers on your bore wall surfaces slide across one another very easily. Instead of metal rubbing against metal, you have Moly platelets moving across one another protecting and lubricating the bore to projectile surface contact

This coating effectively fills in the microscopic pores that cover the surface of all micro bore imperfections making them smoother. By filling in the craters and pores Moly improves this seal

This overlapping coating of Moly also gives protection against loading (perpendicular) forces. The high pressures that occur between these moving surfaces that tend to squeeze normal lubricants out.


ID be sure to use a can of this additive with every oil change,
and not exceed about 7-8 k miles between oil changes:D

btw most paint stores and places like lowes and home depot sell these paint filters dirt cheap,
Id suggest you buy a couple and use them, to filter draining oil as the oil drains out ,
as they are rather useful for rapidly indicating potential engine wear issues
btw hot oil will cause them to fold so you use them dropped into a large funnel as a support structure

you'll want a decent size metal funnel as plastic can get flimsy if subjected to hot oil flow
and you'll want insulating gloves if you're holding a metal funnel full of hot oil, and of course,
a decent container to drain that hot oil into

shop carefully, identical funnels can be found for sale,
that cost $18-over $90 on ebay and amazon
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