Camshaft install tips and tricks
Use this list as a guideline so that you remember to check all these things when installing a new flat tappet camshaft. This list is not gospel, and if the manufacturer of the camshaft you're using recommends procedures that differ from what is shown here, use the manufacturer's recommendations instead.
 Mistakes that may "frag" a flat-tappet camshaft and lifters
1. Failure to remove all rust-preventative from cam and lifters with solvent once you get them home.
This advice does not include removing coatings applied at the factory such as phosphates. It is only suggesting to remove rust-preventative grease that may or may not have been applied to the cam/lifters to prevent rust in storage. This grease will not have the extreme pressure characteristics that Molybdenum Disulphide has and should be removed so that MD can be applied properly. MD is the black, tar-like extreme-pressure grease that is recommended by some camshaft manufacturers to be applied to the lifter crowns/cam lobes for initial flat tappet camshaft break-in.
2. Failure to wash the cam and lifters with hot soapy water to remove the remainder of rust-preventative not removed with solvent.
Caution: wash only the crown of the lifters: the very bottom of the lifter where it contacts the camshaft lobe. Do not allow water to get into the interior of the lifter body. Be very careful here if the lifter has an oiling hole that has been EDM'd into the crown to provide oil from the interior of the lifter body to the camshaft lobe. Before applying molybdenum disulphide, dry the cam and lifter crowns thoroughly with hot air from a hot air gun or hair dryer, to remove all traces of moisture.
Do not use any abrasive materials such as Scotch-Brite pads or sandpaper of any kind to accomplish these solvent and soap cleaning operations. Use only soft, clean rags. The camshaft is cleaned so that rust-preventative oils and greases can be completely removed. If left on the camshaft, such substances might hinder the penetration of an extreme pressure lubricant such as molybdenum disulphide.
3. Failure to properly massage an extreme pressure lubricant such as molybdenum disulphide into the pores of the metal on all lobes and lifter faces.
Molybdenum disulphide will actually bond with the metal and give maximum protection to the lifter crown/lobe. Use the 'moly' lube on the distributor gear, cam lobes and the lifter foot that contacts the lobe only- not the bearing journals, and not the sides of the lifters. Engine oil can be used on the lifter bores and lifter sides, and the pushrod cups of the lifters.
4. Failure to use an extreme pressure lubricant additive in the engine oil for camshaft break-in.
There are many different products for facilitating valid cam break-in. Each cam manufacturer has their own specific product to facilitate valid cam break-in. The aftermarket has also come to our rescue with many different formulations of break in oil and oil additives containing zinc dialkyldithiophosphates (ZDDP).
Most ZDDP additives recommend a specific quantity in the oil for break-in, and then half that amount for each subsequent oil change. Yes, it is possible to get too much ZDDP in the oil and generate spalling of the cam lobes. So do your research. And when in doubt, read the directions!
- ZDDP resources
It is a very good idea to change the oil and filter after the initial cam break in period. Use another dose of ZDDP. This oil and filter can remain for the next 500 miles. After that, change the oil and filter again. Add ZDDP unless the motor oil that's being used contains sufficient quantities for a flat tappet engine.
Resume a normal maintenance routine after the first 500 miles.
5. Actual installation of the camshaft into the block.
On a complete engine assembly, it is often helpful to install the camshaft BEFORE the crankshaft; in many cases the cam would be the first major part to be installed by the assembler after "final cleaning" of the block (the cam bearings and block plugs are likely to be installed by the machine shop). If this is the case, it is helpful to (if possible) set the block on the floor bellhousing-side DOWN, so the block is vertical. The camshaft can then be lowered into the block straight down, so there's minimal effort needed to assure that the cam lobes and cam journals DO NOT nick the bearings. If the cam MUST be installed horizontally, it is mandatory to use a "handle" of some sort on the front of the cam, and to take particular care that the cam doesn't bang into, or scrape across the bearings. Whether vertical or horizontal, if the crankshaft isn't in the way, it's easy to guide the cam through the bearings with one hand while supporting the front end of the cam with the other.
6. Failure to verify "lifter spin" on flat-tappet lifters.
With the camshaft and lifters installed, but before the timing chain is attached or the pushrods are installed, mark each lifter and lifter bore with a "Sharpie" or other marker. A simple stripe on the lifter bore aligned with a dot on the visible part of the top of the lifter is fine. Rotate the camshaft several revolutions, and assure that the lifters spin in the bores, as noted by the increasing misalignment of the dot on the lifter relative to the stripe on the lifter bore. The lifters may not all spin the same amount; some will spin more than others, but they all must show some rotational movement as the cam spins. The only exception to this that I'm aware of is Buick "Nailhead" V-8s, which (at least in OEM form) have no crown on the lifter foot, no taper on the cam lobe, and no offset between lifter bore and cam lobe. The Nailhead lifters are NOT intended to spin.
 Valve springs
7. Failure to use acceptable valve spring pressure for cam break-in.
You can't use 350 lb. over-the-nose springs and expect the cam to live through break-in. Assemble the heads with stock or weak single springs (only if those springs will accept the amount of valve lift and the retainers will clear the valve seals/valve guides) to break in the cam, then use one of the many tools available to change the springs with the heads on the motor. Those without a compressor to hold the valves up for this operation can feed some clothesline cord through the spark plug hole and then bring the piston up to smash the rope and hold the valves up.
Alternatively, assemble the heads with the springs you will run and use reduced-ratio break-in rockers, then change out the rockers after break-in. Although expensive, these are available from Crower in various ratios for different motors. A popular ratio for a small block Chevy would be a 1.3:1 rocker. In other words, let's say the lift at the cam is 0.350" and the theoretical lift at the valve with 1.5:1 rockers is 0.525". Using the 1.3:1 rockers would result in lift at the valve of only 0.455", thus reducing stress at the camshaft/lifter interface during the crucial break in period. Of course, you may have to elongate the pushrod holes to accommodate the longer rocker arm pushrod cup-to-pivot dimension, and/or alter the slots in your guide plates. Be aware that reduced ratio rocker arms will by themselves do nothing to lessen the seat pressure. Things that will change the seat pressure are a different installed height, or a different spring rate. Also be sure to do the math to be sure the reduced ratio rocker arms will reduce the open spring pressure to acceptable levels for break in; don't assume anything.
 Checking clearances
Note: More info on checking clearances at Valve train points to check.
8. Failure to check for valve spring coil bind at max lift.
If you cannot tell by eye, verify by inserting a .010" feeler gauge between the coils. A .010" between five coils would give a total of .050" safety margin before stacking the spring solid. If you cannot pass the feeler gauge between the coils, the spring is either coil bound or dangerously close to this condition, and you have probably over shimmed the spring (the fitted dimension is too short).
9. Failure to check for retainer to valve guide/seal clearance.
1/16"-1/8" (0.0625"- 0.125") clearance at full valve lift is considered sufficient. The valve spring retainer to valve stem seal clearance at maximum lift is the limiting factor with stock L31 Vortec heads. Due to casting and manufacturing tolerances/differences, the retainer to seal clearance has to be checked on each head to determine what the maximum lift is for that head. Reports indicate that 0.450" valve lift is usually no problem, and as much as 0.480" lift has reportedly been used with nothing more than a different valve stem seal being used. GM says the limit is about 0.420" using all stock parts; this is supposed to allow for 0.030" retainer-to-seal clearance. More on the L31 Vortec heads here.
10. Failure to check for binding at the rocker/stud interface with stamped steel rockers.
Long slot rockers are made specifically to cure this problem. Quality roller rockers with a needle bearing trunnion are as good as it gets with a stud-mounted rocker.
11. Failure to check for piston/valve clearance
0.080" on the intake and 0.100" on the exhaust is considered by many to be the minimum clearance acceptable. You will probably find the closest near-miss at the exhaust valve on overlap, when the piston is chasing the exhaust valve back onto its seat.
12. Failure to clearance lifters in their bores.
Lifter clearance should be 0.0012" to 0.002", with 0.0015" (one and one half thousandths) considered close to ideal. Too loose can be as bad as too tight. One way to provide a flat tappet cam and lifters with additional lubrication is to groove the lifter bores. One tool for doing this operation is the Comp Cams p/n 5003 lifter bore grooving tool sold by Summit. Solid lifter flat tappet lifters are available with a small machined hole in the lifter foot that feeds pressurized oil to the interface between the cam and lifter. But having that hole is no guarantee (see photo below)...
 Engine RPM for break in
13. Failure to run the motor at 2500 rpm or higher (alternating 500/1000 rpm up and down) to allow the crank and rod big ends to throw oil onto the cam, for a minimum of 30 minutes.
Warning: No idling! The motor should not be run at less than 2500 rpm for a minimum of 20 minutes. If a problem develops, shut the motor down and fix it, then resume break-in. The main sources of camshaft lubrication is oil thrown off of the rods and crankshaft, drain back from the oil rings and oil blowing around inside the crankcase (this is known as "windage"). At idle, the crank isn't spinning fast enough to provide sufficient oil splash to the camshaft/lifters for proper break in protection.
14. Failure to initially adjust the valves properly.
Using the "spin the pushrod until it feels tight" method may result in valves too tight. Holding the rocker arm tip down against the valve stem tip with one hand, jiggle the pushrod up and down with your thumb/forefinger of your other hand until all play is removed, then turn the rocker nut the number of times specified by the lifter manufacturer to set the preload. (Another good reason to buy lifters from someone you can talk with about them on the phone instead of buying them in a white cardboard box with no name on it). Builders who have done hundreds of engine builds may have the "feel" to do the "twist" method, but those who are doing their first few builds lack the experience to do this and will have better results with the "jiggle the pushrod up and down" method.
15. Failure to inspect the distributor drive gear for wear.
Too much wear can allow the cam to walk in its cam bore and contact an adjacent lifter. The builder is also responsible for using a distributor gear that is compatible with the camshaft gear material. Coordinate this with the cam grinder before you ever begin assembling the motor. Hardly anything will make you feel more stupid than finding one or the other of the gears eaten up, necessitating an engine tear-down to clean out all the shrapnel.
16. Failure to have everything ready for the motor to fire on the first few turns.
Fully charged battery, good starter, known-good carburetor with full fuel bowl, source of fuel to the carburetor to allow minimum 20 minutes of uninterrupted running. Ignition timing set. Warning: no grinding on the starter!
 Pre-lube engine oil system
The lifters can be dipped into a container of oil but unless the manufacturer's instructions tell you otherwise, there's no need to pump hydraulic lifters up before installing them. There are some exceptions to this. For instance Rhodes lifters DO recommend their "original" lifters be pumped up prior to installing, then for them to be adjusted to 3/4 of a turn, or so the lifter cup is about 1/16" below the retainer.
17. Failure to prime the oiling system prior to firing the motor.
Prime until you get oil out of the top of each and every pushrod. Observe the oil pressure gauge to be certain that pressure is registering. Priming will aid lubing the valve train at initial start up. It's the last area of the motor to get lubed on dry start. You can make a tool by disassembling an old distributor and removing the gear, or just grinding off the gear teeth so that the teeth don't engage the cam teeth. Or, you can spring for 20 bucks and get a very nice priming tool that will be a nice addition to your tool chest. In either case, you will NOT get oil to the passenger side rockers of a Chevrolet-designed V-8 unless you use either the distributor or the tool to block off the oil galley under where the distributor bolts down. An example of a tool for use with a Chevrolet engine is the Proform oil pump prime tool.
Engines with an oil pump that is not driven by the distributor like the GM LS-series, Vega 2.3L, some later Buick V-6, etc. can be primed by injecting pressurized oil into the oil pressure gauge port. A hand-pumped garden-sprayer-type pressure vessel will work if you can adapt the end of the hose to appropriately-threaded fittings to suit the port in the block. Put the engine oil into the pressure vessel, pump the handle, squirt all the oil into the oil sender port. The pressure used doesn't really matter--if the oil squeezes into the engine at two or five psi...that's just fine.
Priming is not intended to initially lubricate the internal engine components. Every moving part should have received lubrication when the engine was assembled. Priming the oil system is a process to remove air from the pressurized portions of the oiling system, i.e. the oil pump, the oil filter, and some of the oil galleries (the oil galleries will begin to drain the oil as soon as the priming stops but the oil pump and filter are likely to remain full.) Priming is "done" when you see oil pressure on the gauge, plus about ten or fifteen seconds additional. Often the crank will also be rotated two revolutions while the priming is being done to allow all the lifters to see pressurized oil from the lifter oil gallery.
With engines that use a submerged oil pump (Chevrolet big- and smallblocks, Oldsmobile V8, Pontiac V8, etc.), priming is usually done in less than one minute. Engines with non-submerged oil pumps (Buick V8, big Cads for example) may take longer due to the difficulty in pulling oil through the long pickup tube to the remote-mounted pump. However, once you show pressure on the gauge, another ten or fifteen seconds is entirely sufficient. There is NO need to prime until the oil squirts over the fender; in fact some engines won't show oil at the rocker arms until it's running.
18. Failure to use a new cam and lifters.
Used lifters should only be used on the very same cam, in the very same block, and in the very same positions they were removed from. Chances that the lifter bores will be machined on the very same angles on a different block as the block the lifters came out of are about equal to you hitting the lottery. If you purchase a used flat tappet cam from a swap meet or yard sale, plan on using it for a doorstop. New lifters should not be used on an old cam, either. Given the reasonable cost of a new cam and lifter set (~$100 ca. 2012), vs. the cost of cleaning and repairing the damage done by a failed cam and lifters, the choice to use new parts is obvious.
19. Failure to observe the lifters and pushrods turning with the motor running. If the lifter is not turning, the cam lobe is hitting on the same spot on the lifter every revolution and it won't be long until the lifter yields and then takes the lobe out with it. All lifters and all pushrods must be turning for successful engine operation.
That pencil-point of contact between the camshaft lobe and lifter crown is under somewhere between 250,000 and 300,000 pounds per square inch of pressure, so it should come as no surprise that extreme pressure lubrication is required, especially at break in where the contact point between lobe and lifter is irregular. The break in grease applied to the bottoms of the lifters and to the cam lobes is all the lubrication there is during the initial 5 to 10 seconds of operation, until motor oil reaches the interface.
 Comp Cams's position on break-in additive and nitriding
"Due to federal legislation, motor oils no longer contain certain anti-scuffing agents that played a critical role in flat tappet camshaft break in. While incorrect valve spring pressure and not following proper break-in procedure are often the culprits, the changes in oil formulation have brought about a need for additional steps to be added to the break-in process.
COMP Cams has two ways to ensure proper break-in of flat tappet cams. COMP Cams Engine Break-In Additive (part #159) ensures that the camshaft will have the lubricants that it needs to seat the camshaft journals and lobe/lifter surfaces. This lubricant is poured into the engine crankcase after the camshaft and lifters have been coated with the initial break-in lubricant (molybdenum disulphide) supplied with the camshaft.
Another option for increasing flat tappet cam longevity is nitriding. Recently COMP Cams invested in a nitriding machine, the first of its kind owned by a major U.S. aftermarket camshaft manufacturer. Nitriding actually hardens the surface of the camshaft and tappet face by injecting nitrogen “needles” into the metal. The result is an ultra-hard surface on the face of the camshaft lobes and lifter face, which greatly improves the performance and break-in process for flat tappet cams. This process is an additional charge for COMP Cams camshafts, but for many extreme duty applications, it virtually ensures proper break-in and increased durability."
 Racer Brown's position on oil level during break-in
Racer Brown is a world-renowned camshaft manufacturer/engineer who ground the hot cams for Chrysler Corporation during the horsepower wars of the 60's.
"Overfill the crankcase by at least 4 or 5 quarts of oil so that the oil level comes to within an inch of the top of the oil pan. Install a set of fairly hot spark plugs with a gap of 0.050" to 0.060" to prevent oil-fouling of the plugs, which is otherwise inevitable under no-load conditions with all the extra oil aboard. During this operation, we want near-maximum oil flow, together with a maximum of oil vapors and liquid oil thrashing about in the crankcase so that the cam lobe and lifter interface lubrication is considerably better than marginal."
 Lubrication requirements after break in
For the same reasons break in oil or break in oil additives are used to break in the cam and lifters, after cam/lifter break in, only oils formulated for flat tappet equipped performance engines should be used. Also acceptable is using additives like ZDDPlus, etc. (in the correct quantity- less than for initial break in) added to over the counter motor oil.
- Molybdenum disulfide
- Zinc dithiophosphate
- Comp Cams Engine Break-In Oil Additive
- Hotrodders forum thread on cam and assembly lubricants
- How break-in oils are different than the rest and why you need them Engine Builders Magazine
 Adjusting the cam timing or "phasing"
Cam phasing is the relationship of the camshaft position to the crankshaft position in reference to TDC. A change of 2 degrees at the cam gear equals 4 degrees at the crank.
Note: When advancing/retarding the cam, be sure to check valve to piston clearance. Each degree of change effects valve clearance approximately 0.010". Example: If you advance the camshaft 4 degrees, you will lose about 0.040" clearance between the intake valve and piston, and you will gain about 0.040" clearance between the exhaust valve and piston. It will be the opposite if the camshaft is retarded.
The cam timing, or phasing, can be changed at the time of installation by using a multi-keyway timing set, or an adjustable cam gear like Cloyes Hex-A-Just.
On timing sets that have no built-in adjustability, the cam phasing can still be adjusted in many cases. This is done by drilling the dowel pin hole of the cam gear oversize in order to use a bushing to advance or retard the cam gear. On engines where this isn't practical, an offset crank gear Woodruff key can often be used instead.
In the majority of cases, installing the cam "straight up" (without any advance/retard added by the installer) is the correct way to install the cam and timing set. Many cam makers have already advanced (in most cases) the cam timing when the cam was made to suit the application. Unless the builder has access to an engine dynamometer or has advanced knowledge of the dynamics involved, advancing/retarding a cam is nothing but a shot in the dark as to whether it will result in any benefits at all. And there's the chance the engine output could be adversely affected by indiscriminately changing the phasing of the cam. The piston to valve clearance can be reduced enough to cause damage in some cases.
 Effects of changing cam timing
 Advance timing
- Open Intake Valve Sooner
- Builds more low-end torque
- Decreases piston to intake valve clearance
- Increases piston to exhaust valve clearance
 Retard timing
- Keeps intake valve open later
- Builds more upper RPM power
- Increases piston to intake valve clearance
- Decreases piston to exhaust valve clearance
- Also see Phasing the camshaft
 Effects of changing lobe separation angle
The lobe separation angle (LSA) is ground into the cam at the time of manufacture and cannot be changed by the installer.
 Widen (larger) LSA
- Raises torque to higher RPM
- Reduces maximum torque
- Broadens power band
- Reduces maximum cylinder pressure
- Decrease chance of engine knock
- Decrease cranking compression
- Decrease effective compression
- Idle vacuum is increased
- Idle Quality improves
- Overlap decreases
- Natural EGR effect is reduced
- Increases piston-to-valve clearance
 Tighten (smaller) LSA
- Moves torque to lower RPM
- Increases maximum torque
- Narrow power band
- Builds higher cylinder pressure
- Increase chance of engine knock
- Increase cranking compression
- Increase effective compression
- Idle vacuum is reduced
- Idle quality suffers
- Overlap increases
- Natural EGR effect increases
- Decreases piston-to-valve clearance
 Roller cams are not immune
While the move has been made by the OEMs to stop using flat tappet cams and lifters in production vehicle engines (replaced by hydraulic roller cams and lifters), they are not immune to failure.
The same type of oil additives should be used, because it is not just the cam and lifters that require a high pressure lubricant additive; the however do not use the heavy moly cam break in lube on a roller cam or lifter- it will cause much more problems than it will cure. Instead, follow the manufacturer's instructions. If those are not available for some unknown reason (all should be found online), use motor oil or a roller lifter-specific lube for the roller lifters and cam.
- Camshaft Break-In Guide - How To Break In That Flat-Tappet Cam Car Craft, August, 2011
- Cam design
- Crankshaft Coalition Wiki articles
- How to choose a camshaft
- Cam and compression ratio compatibility
- Adjusting hydraulic lifters
- Adjusting solid lifters
- How to prep and start a rebuilt engine
- Valve train points to check
- Valve train geometry
- Pushrod length checking tool, homemade
- Valve spring tech
- Adjust valves
- Camshaft tech by Dimitri Elgin
- Hotrodders forum threads