installing the cam & breaking in a new engine

installing the cam & breaking in a new engine

Postby grumpyvette » October 10th, 2008, 12:43 pm

If you fail to read thru the linked info youll miss a great deal of related info you may NEED ... index.html







viewtopic.php?f=52&t=2166&p=5840&hilit=bore+groove#p5840 ... index.html ... ducts.html ... hp?t=80815

notice the approximate location and relationship between the cam pin and crank key

you may want to keep in mind that theres a huge variation in the quality of the metal and machine work in both the surface finish and hardening or rockwell numbers between different manufacturers and some of the cheaper imported lifters and cams are much softer and more prone to wear than the better brand name components, contrary to what you may think theres some advantage in paying for brand name vs bargain basement components, manufacturers LIKE, ERSON, LUNATI CRANE OR CROWER, have, standard, or premium lifters available with micro- polished surfaces and hardened components, and in some cases hardened cams and premium cores for an additional charge, over the cost of the base line products , but even those base products tend to be superior to many imports

Cam Break-in Procedure

• 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.


moly cam lobe and some zddp helps

Break-In Tips

With a freshly rebuilt engine, the first 10-20 minutes of its life are probably the most important. During break-in, the piston rings seat against the cylinder walls, and the cam and lifters establish their life-long wear pattern. The day that you actually start the engine for the first time, have a few buddies help out during the break-in. As soon as the engine fires, have one buddy concentrate on actuating the throttle to keep it at a steady rpm--about 2,000 rpm. Then, use a timing light to set (or double-check) the ignition timing. Have one buddy stand back and monitor the entire break-in process. If oil or fuel begin to leak, or if smoke begins to develop, your "spotter buddy" can alert you to potentially bad developments so they can be immediately remedied.
run a garden hose thru the radiator fins, and use a fan blowing on the radiator to keep the coolant temps low, and be sure the coolant and oil levels are correct before you start,

After the engine has run for about 10 minutes, begin varying the engine speed between 1,500-4,000 rpm for about five-ten minutes. Afterward, determine if the engine will idle on its own. If not, timing and/or carburetor adjustments may be needed.

Once the engine receives about 30 minutes of break-in time, shut it off, and let it cool for a few hours. Drain the engine oil that will likely be contaminated with assembly lube and microscopic bits of metal worn off during the break-in process. Pour in new engine oil, and install a new oil filter. Once the cylinder heads have cooled, pull the spark plugs one at a time to determine their operating condition--lean, fuel fouled, oil fouled and so on. Be sure to check the condition of the spark plug wires, making sure that none have been burnt during engine break-in.

Finally, carefully inspect the entire engine checking for oil, fuel or coolant leaks that may have developed. Oftentimes, after the engine has heated up during break-in, various bolts will loosen up slightly--especially exhaust header and intake manifold bolts.

these instructions were included with a rebuilt engine

Break-in and Installation Instructions

1.) Drive normally but not a continuous high speeds for the first 500 miles. Occasional quick bursts of speed followed by quick deceleration during this period, is beneficial. AVOID LUGGING!!! TRIPS AND TOWING are not recommended until after 1000 miles.

Applying loads to the engine for short periods of time causes increased ring pressure against cylinder walls and helps to seat the rings. This is especially important because you are "BREAKING-IN" the engine with heavy duty oils. The rapid deceleration increases vacuum and gives extra lubrication to the piston and other assemblies.
2.) IMPORTANT! AFTER 500 TO A MAXIMUM OF 1000 MILES OF SERVICE, change oil and filter and readjust the valves, except hydraulic. We also require that valve adjustments be done again after a total of 6000 miles. We require a maximum of 3000 miles between oil changes and factory recommendation on valve adjustments thereafter.

Add oil at 1/2 quart intervals on small capacity engines. OIL AND WATER LEVELS ARE A DRIVER OR OWNER MAINTENANCE RESPONSIBILITY, THEY MUST BE KEPT FULL. We realize that this means extra effort on your part, but it assures long and satisfactory engine performance.
3.) A heavy duty detergent oil is required. Use a good quality brand oil, Some Manufacturers require 5/30, others recommend 10/40 for 20 degrees Fahrenheit to 100 degrees Fahrenheit and use 20/50w for higher temperatures and heavy duty use.

In past years, it has been common practice to use non-detergent and straight weight oil during the "BREAK-IN" period because it was felt that the rings would seat quicker without the film strength additives. More recently, there has been a trend to high speed and high temperature engines, cam lobe and tappet loads also have increased to a point where it is important to use heavy duty oils which contain a EP (high pressure) additive right from the start. Rings will seat properly when moderate loads are applied as noted above in section one.
4.) Keep your engine in tune. Tune-up specifications should always be to the manufacturers recommended specifications.
5.) PLEASE! If you experience any trouble or even suspect a problem please contact us IMMEDIATELY! It is easier and cheaper to fix a little problem than a big one.

1.) Determine why old engine failed. Check catalytic converter or computer controlled parts, check engine warning light codes, radiator, water pump, etc. Do not install replacement engine with defective components, this could cause premature failure.
2.) Compare rebuilt engine with old engine as to crankshaft flange, pilot hole and bearing, oil pan, timing cover, engine mounting provisions and cylinder head mounting holes.
3.) Prime the oil pump in any acceptable Industry Standard Method! This is very important.
4.) All related parts not furnished by us should be thoroughly cleaned.
5.) If original engine has blown and scattered pieces, such as piston particles, you Must thoroughly inspect intake manifold for foreign material to avoid destroying the new engine.
6.) Make sure that dipstick tube and dipstick are of proper length to register required amount of oil.
7.) Check motor mounts for oil soak and parting of rubber from metal.
8.) Radiator should be flow tested and thoroughly cleaned if necessary.
9.) Check radiator cap for application and operation.
10.) Replace thermostat to avoid possible failure.
11.) All hoses, radiator, heater, and by pass should be replaced if necessary.
12.) A heavy duty detergent oil is required. Use a good quality brand oil, Some Manufacturers require 5/30, others recommend 10/40 for 20 degrees Fahrenheit to 100 degrees Fahrenheit and use 20/50w for higher temperatures and heavy duty use.
13.) Always replace oil filter cartridge and flush any cooler lines. And replace oil cooler if contaminated.
14.) Oil pressure and temperature sending units may need to be replaced because they have a tendency to leak oil and register improper after a reinstall.
15.) Always install new spark plugs of proper heat range and check to make sure the spark plug wires are in good condition.
16.) Check distributor, advance controls and distributor cap for cracks.
17.) Water pump should be checked for signs of leaking.
18.) Clutch fan should be checked for proper operation.
19.) Fan belts should be checked for cracks and other defects.
20.) Check fuel pump for oil leak at pivot pin and also for fuel leaks.
21.) Check heat riser valve for proper operation.
22.) Replace paper air filter or clean oil type.
23.) Check smog components and computer sensors. Replace defective or old parts.
Make sure radiator is full of coolant (at least 50% water and 50% antifreeze) and Engine Block is filled full before attempting to start engine.
CAUTION: Air Locks can ruin a new engine.
25.) When filling radiator make sure it is filled to proper capacity and that there are no air locks, as this can cause cracking of cylinder block and heads.
26.) Start engine, check oil pressure, adjust ignition timing to manufacturers specifications and adjust carburetor after engine has warmed up fully. Also, at this time be sure to check for any water or oil leaks.
27.) Take the car for a road test. After road testing the vehicle recheck installation, oil and water levels, look for any leaks, recheck timing and adjust carburetor if necessary. Please refer to "BREAK IN PROCEDURE" sheet for further information.
See Warranty Addendum #8

NOTE: After at least 1 hour running time and engine has cooled, retorque head and adjust valves to manufacturers specifications. On Required engines if you are not sure if this is required on your engine ASK!


Every effort has been made to accurately supply the proper item, however it is the responsibility of the installing mechanic to verify engine and parts for correct size and application by comparing the old parts. This is due to the many combinations available on the market today. You are responsible for the correct installation of the engine. The engine life and performance depends on a good professional installation. Follow the instructions carefully. Seek professional help if you are uncertain about ANYTHING!

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Re: installing the cam & breaking in a new engine

Postby grumpyvette » November 4th, 2008, 10:39 am

IT should be obvious that you'll need to pre-prime the blocks oil passages and adjust the rockers so oil flows from the rockers with the engine being pre-primed with a priming tool being used BEFORE trying to start any engine with a new cam to insure oil flow begins instantly on the engines start-up,you WON,T get oil to all lifters equally unless the engines crank & cam are spinning,(so during testing spin the engine slowly with a breaker bar or ratchet), because the oil passages feeding the lifters aligns differently at different lifts,your oil leak at the distributor base is normal, but the clearances and flow may be excessive, with a priming tool, some are not nearly to spec. ID measure the diam. of the oil pump primer and then measure the distributor base, Id bet the distributor base is larger and fits better, which reduces the potential for leakage.
those bottom two bands form a wall on the oil passage, some guys cut a rounded grove and install an O-RING so the upper band seals too the block, you don,t want to do that to the lower band simply because that's the oil flow source to the distributor /cam gear
20 psi is about normal for your typical 3/8 drill,max pressure is not nearly as important as checking flow, and for leaks where there should not be leaks, with an engine primer tool,Ive brazed a socket to the top of my oil pump primer and use the 1/2" drive air ratchet to drive it, it won,t heat up and burn up like a electric drill will.
don,t get alarmed if you get zero pressure or flow for a few seconds,(the oil filter and passages need to fill first) that's one reason WHY your pre-priming, to get oil flow to the bearings instantly on start up , you don,t want them running without oil flow if you can prevent it even for 20 seconds

the tools use is more a tweak or refinement than mandatory, but increasing cool lubricant flow to the lifter contact area can,t hurt a bit!I bought mine simply because I liked the idea, and its proved to be useful.
I usually groove my blocks lifter bores lower 1/3rd regardless of the lifter type used, but Id point out that the grooves are shallow and designed to flow extra cooling lubricant, so you'll want to also use a windage tray to control the extra coolant flow volume.
I don,t think they are as big a benefit to roller cam applications, as the flat tappet lifter applications but obviously your more or less stuck with the grooves in the lifter bores even if you change lifter types after the lifter bores grooved unless you sleeve them.



New or Rebuilt Engine Break-in Procedure

A recommended engine break-in procedure.
This is a summation of many articles on the subject found on the internet. Some of the information is from MOTORCYCLIST Feb. 1991, titled GIVE IT A BREAK-IN (How to make your bike run stronger and live longer), and some is from a Textron Lycoming "Key Reprint" article.
The first few hundred miles of a new engine's life have a major impact on how strongly that engine will perform, how much oil it will consume and how long it will last. The main purpose of break-in is to seat the compression rings to the cylinder walls. We are talking about the physical mating of the engine's piston rings to it's corresponding cylinder wall. That is, we want to physically wear the new piston rings into the cylinder wall until a compatible seal between the two is achieved.
Proper engine break in will produce an engine that achieves maximum power output with the least amount of oil consumption due to the fact that the piston rings have seated properly to the cylinder wall. When the piston rings are broken in or seated, they do not allow combustion gases to escape the combustion chamber past the piston rings into the crankcase section of the engine. This lack of "blow-by" keeps your engine running cleaner and cooler by preventing hot combustion gases and by-products from entering the crankcase section of the engine. Excessive "blow-by" will cause the crankcase section of the engine to become pressurized and contaminated with combustion gases, which in turn will force normal oil vapors out of the engine's breather, causing the engine to consume excessive amounts of oil.
In addition to sealing combustion gases in the combustion chamber, piston rings must also manage the amount of oil present on the cylinder walls for lubrication. If the rings do not seat properly, they cannot perform this function and will allow excessive amounts of oil to accumulate on the cylinder wall surfaces. This oil is burned each and every time the cylinder fires. The burning of this oil, coupled with "blow-by" induced engine breathing, are reasons that an engine that hasn't been broken in will consume more than its share of oil.
When a cylinder is new or overhauled the surface of it's walls are honed with abrasive stones to produce a rough surface that will help wear the piston rings in. This roughing up of the surface is known as "cross-hatching". A cylinder wall that has been properly "cross hatched" has a series of minute peaks and valleys cut into its surface. The face or portion of the piston ring that interfaces with the cross hatched cylinder wall is tapered to allow only a small portion of the ring to contact the honed cylinder wall. When the engine is operated, the tapered portion of the face of the piston ring rubs against the coarse surface of the cylinder wall causing wear on both objects.
Each tiny groove acts as the oil reservoir holding oil up to the top level of the groove where it then spreads over the peak surface. The piston ring must travel up and down over this grooved surface, and must "hydroplane" on the oil film retained by the grooves. Otherwise, the ring would make metal-to-metal contact with the cylinder wall and the cylinder would quickly wear out.

However the ring will only ride on this film of oil if there is sufficient surface area to support the ring on the oil. When the cylinders are freshly honed the peaks are sharp with little surface area. Our goal when seating the rings on new steel cylinders is to flatten out these peaks to give more surface area to support the rings, while leaving the bottom of the groove intact to hold enough oil to keep the surface of the cylinder wet with oil. See illustration. At the point where the top of the peaks produced by the honing operation become smooth and the tapered portion of the piston ring wears flat break in has occurred.
When the engine is operating, a force known as Break Mean Effective Pressure or B.M.E.P is generated within the combustion chamber. B.M.E.P. is the resultant force produced from the controlled burning of the fuel air mixture that the engine runs on. The higher the power setting the engine is running at, the higher the B.M.E.P. is and conversely as the power setting is lowered the B.M.E.P. becomes less.
B.M.E.P is an important part of the break in process. When the engine is running, B.M.E.P. is present in the cylinder behind the piston rings and it's force pushes the piston ring outward against the coarse honed cylinder wall. Piston rings are designed to take advantage of the pressure and us it to push the rings out against the cylinder wall. Therefore, as pressure builds during the compression stroke, the rings are pushed harder against the cylinder wall which aids in seating the rings.
The higher the B.M.E.P, the harder the piston ring is pushed against the wall. The surface temperature at the piston ring face and cylinder wall interface will be greater with high B.M.E.P. than with low B.M.E.P. This is because we are pushing the ring harder against the rough cylinder wall surface causing high amounts of friction and thus heat. The primary deterrent of break in is this heat. Allowing to much heat to build up at the ring to cylinder wall interface will cause the lubricating oil that is present to break down and glaze the cylinder wall surface. This glaze will prevent any further seating of the piston rings. If glazing is allowed to happen break in will never occur. Also, if too little pressure (throttle) is used during the break-in period glazing will also occur.
Most people seem to operate on the philosophy that they can best get their money's worth from any mechanical device by treating it with great care. This is probably true, but in many cases it is necessary to interpret what great care really means. This is particularly applicable when considering the break-in of a modern, reciprocating engine.
For those who still think that running the engine hard during break-in falls into the category of cruel and unusual punishment, there is one more argument for using high power loading for short periods (to avoid excessive heat) during the break-in. The use of low power settings does not expand the piston rings enough, and a film of oil is left on the cylinder walls. The high temperatures in the combustion chamber will oxidize this oil film so that it creates glazing of the cylinder walls. When this happens, the ring break-in process stops, and excessive oil consumption frequently occurs. The bad news is that extensive glazing can only be corrected by removing the cylinders and rehoning the walls. This is expensive, and it is an expense that can be avoided by proper break in procedures.
We must achieve a happy medium where we are pushing on the ring hard enough to wear it in but not hard enough to generate enough heat to cause glazing. Once again, if glazing should occur, the only remedy is to remove the effected cylinder, re-hone it and replace the piston rings and start the whole process over again.
We asked four top motorcycle engine builders what they do to ensure peak power output and optimum engine life. Here is a capsulation of their responses.
"If the wrong type of oil is used initially, or the break-in is too easy, rings and cylinders could (read will) glaze and never seal properly. A fresh cylinder wall needs some medium to high engine loading to get the piston rings to seat properly for good compression but make sure you don't lug or overheat the engine. Use high quality, low viscosity oil (Valvoline 30 weight), no synthetics, too slippery. If synthetics are used during initial break in the rings are sure to glaze over.
An engine's initial run should be used to bring oil and coolant (air, oil, and/or water) up to operating temperature only, with little or no load, then shut down and allowed to cool to ambient temperature. This is important. After each run the engine needs to completely cool down to ambient temperature. In Texas, especially in the summer, that's still pretty hot. After a cool down period, start it up again and take the motorcycle for it's fist ride (you hope).
This time give the engine light loads at relatively low rpm and stay out of top gear. Lugging the engine, i.e., low RPM with a lot of throttle (manifold pressure), is more detrimental than high rpm. Another key is too constantly vary engine load during the entire break-in period. A constant load is not ideal for breaking in bearing tolerances. This second run should last only 10-15 minutes before another complete cool down.
The third run should see slightly higher rpm with light to medium power loading using short bursts of acceleration to help seat the rings. Again 10-15 minutes of running should do it and again avoid top gear. A forth run should consist of light to medium engine loads with a few more bursts of medium-high rpm, and lasting just 10-15 minutes varying the engine load and again avoiding top gear. Next while the engine is still warm drain the oil and change the filter. This gets out the new metal particles that are being worn away. Most of the metal particles will break away within the first 50 -75 miles. To ensure the rings seat well, use the same high quality oil and don't be shy about short duration high rpm blasts through the lower gears after the oil has been changed.
A few more 15-20 minute sessions should be used to work up to the engine's redline gradually increasing the engine loads. After some definite hard running and 250-500 miles it's a good idea to check the valves. After 500 miles re-torqueing the head is suggested. Switch to synthetic oil but not before 500-1500 miles. Most of the engine experts warned of the danger of breaking in the engine too easily and ending up with an engine that will always run slow whether it is from tight tolerances, inadequate ring seal or carbon buildup. Engine load is more detrimental than rpm because of the head created internally, so avoid lugging the engine but rev it freely especially in the lower gears. Basically, be sure not to get it too hot but be sure to seat the rings properly.
So that's it, sure a lot different than keeping under 4000 rpm for 500 miles then under 5000 rpm for 1000 miles. Maybe bike manufacturers are being super cautious at the expense of your motor's performance? I think that they take the cautious route that works over time (1000 miles, or about 20 hours of break in) versus a faster route that can be more easily screwed up."

billet cams can and do have steel distributor gears that are not compatible with stock cast iron or melonized stock distributor gears, so anytime you change cams get and correctly install the matching distributor gear
keep in mind theres a VAST difference in the QUALITY of bronze distributor gears and alloys vary wildly so its best to both use the cam manufacturers input during selecting components and not to assume all bronze gears are interchangeable

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Re: installing the cam & breaking in a new engine

Postby grumpyvette » August 8th, 2010, 10:00 am

Push Rods & Lifters

Original equipment pushrods have not changed much, but there is a growing demand in the aftermarket for stronger, stiffer pushrods for performance engines.

By Larry Carley

Larry Carley

The pushrods and lifters work with the camshaft and rocker arms to open the engine's valves. This basic setup has changed little since the earliest days of pushrod engines. The only major change in these components has been roller lifters replacing flat bottom lifters on late model engines. Even so, there's still a market for flat bottom lifters in older street performance engines and circle track engines (including NASCAR).The market for pushrods has also been declining, but is still a long ways from disappearing anytime soon. One domestic pushrod supplier we spoke with said it is currently making 62 million pushrods a year for everything from motorcycles to passenger cars, light trucks and diesels.

Original equipment pushrods have not changed much, but there is a growing demand in the aftermarket for stronger, stiffer pushrods for performance engines. Stock pushrods only have to deal with relatively light spring loads (less than 200 lbs.) and lower engine speeds (less than 6,000 rpm). Pushrods in performance engines, by comparison, may be working to overcome spring pressures of 800 lbs. or higher, and engine speeds of up to 9,500 rpm. That's an entirely different operating environment that requires much greater strength and stiffness.

One-piece 4130 chrome moly pushrods have long been the standard for upgrading valvetrain performance. This material has a tensile strength that ranges from 140,000 to 240,000 psi depending on the heat treatment it receives. But nowadays, you can get 4130, 4135, 4140 or even bimetal pushrods with an aluminum inner liner that adds reinforcement with little increase in weight. Pushrods made of 4140 chrome moly can provide up to 275,000 psi of tensile strength with the right heat treatment.

Pushrod wall thicknesses of .080" to as much as .188" are also available today for performance engines that demand increased stiffness. For some Top Fuel drag racing applications, solid pushrods are even available (the rocker arms are lubricated by other means).

Larger diameter pushrods are also available to reduce flex and increase strength. Standard sized 5/16" and 3/8" diameter pushrods can be replaced with 7/16", 1/2", 9/16" and even 5/8" pushrods where clearances allow it. Most of the circle track racers are limited to a maximum pushrod diameter of 7/16", but many drag racers are now using the larger 1/2" to 5/8" diameter pushrods in their motors. Most are using straight tubing, but others are using tapered pushrods to get increased strength and stiffness in the critical lower area where loads are greatest.

For performance applications, many engine builders prefer to use one-piece pushrods rather than three-piece pushrods that have the ends welded on. The ends on a one-piece pushrod are CNC machined to conform to the recessed cups in the rocker arm and lifter. It works as well as a welded steel ball, but adds cost.

The hardened ball on the end of a stock three-piece pushrod or even a chrome moly pushrod can break off under racing conditions. But there are alternatives to going with a more expensive one-piece pushrod. One supplier said it has changed the way it welds the hardened steel ball onto the end of the pushrod. Instead of just cutting the tubing off flat and welding on the ball, they now radius the end of the tubing to match the circumference of the ball. The result is a weld that has about 300 percent greater contact area and increases the shear strength to 12,000 psi - which is about three times stronger than before with only a small increase in cost.

Another pushrod supplier said it is switching to a new centerless grinding process to finish its pushrods, resulting in a much straighter pushrod. The new pushrods will be available around the beginning of 2008 in .050" length increments for all popular applications.

How Important Is Weight?
Common sense tells us that reducing the weight of the pushrods increases the rpm potential of the valvetrain, and reduces the spring pressure needed to maintain valve control at high rpms. But as racers have learned, weight is much more critical on the valve side of the rocker arm than the pushrod side. Why? Because of the leverage effect of the rocker arm.

If a rocker arm were a straight 1-to-1 ratio with no multiplication in lift, any increase in weight on either side of the rocker would have the same net effect. But most rockers have a 1.5, 1.6, 1.7 or even higher lift ratio. This means the valve end of the rocker travels much further vertically than the pushrod end. The leverage effect of the rocker arm ratio multiplies the force exerted by the spring as it shoves the pushrod back down to keep the lifter from jumping off the cam lobe. So if the pushrod is a little heavier but a whole lot stiffer, it doesn't really hurt anything. In fact, it really helps high rpm power by reducing pushrod flex and valvetrain harmonics that can cause the valves to bounce and float.

A lot of engine builders say they have found gains of 15 to 25 horsepower on the dyno by just changing the pushrods in an engine to a stronger, stiffer design. Others are finding even more power by playing around with pushrod lengths and different rocker arm ratios and styles.

Increasing the lift ratio adds horsepower with little or no loss in low rpm torque, idle quality or vacuum. By opening and closing the valves at a faster rate, the engine flows more air for the same number of degrees of valve duration. High lift rocker arms also reduce the amount of lifter travel needed to open the valves, which reduces friction and the inertia of the lifters and pushrods that must be overcome by the valve springs to close the valves.

On the other hand, increasing the rocker ratio also increases the effort required to open the valves because of the leverage effect. The higher the rocker arm ratio, the greater the force the camshaft, lifters and pushrods have to exert to push the valves open, and the stronger the pushrods have to be to keep from bending. That's why everyone is clamoring for stronger, stiffer pushrods today.

Many pushrod suppliers offer custom-made pushrods in special lengths, diameters or materials. Ordering a set of custom pushrods may be just the thing to squeeze a little more horsepower out of an engine, but they are not cheap. A set of custom-made pushrods can cost as much as $50 to $60 or more each!

The finishing that goes into a pushrod can also vary, depending on the supplier and how much you are willing to spend. Some suppliers polish their pushrods to give them a nice, chrome-like finish. Others may apply special coatings to reduce friction in engines that use pushrod guide plates. One supplier said it inspects every pushrod it makes for NASCAR applications with magnetic particle inspection as a final quality control check.

Pushrod Length
The length of a pushrod will depend on a variety of factors: the base circle of the camshaft (higher lift cams with reground smaller diameter base circles will require longer pushrods) and the height and location of the lifters; whether the pushrod cups in the lifters are offset or centered; the location of the pushrod cups or adjuster screws in the rocker arms; the geometry of the rocker arms and rocker arm ratio; the installed height of the valves; and how much the cylinder heads or block have been milled.

With so many variables, it's important to get the correct length pushrods so the tips of the rockers will be properly positioned on the tops of the valve stems. If the pushrods are too short, the rocker arms may exert a side thrust against the valve stems as they push the valve open. This can increase friction, valve stem and guide wear, and increase the risk of valve stem breakage. If the pushrods are too long, the valve spring coils may bottom out and bind at maximum valve lift, causing damage to the valvetrain (typically a bent pushrod).

Most professional engine builders know how to measure pushrod length, and how to determine the correct length pushrod for a given camshaft, cylinder head and valvetrain combination. Adjustable length pushrods are available to make the job relatively easy, assuming you know where and how to measure.

To determine the right length, an adjustable pushrod is installed in the engine. The length of the pushrod is then adjusted so the roller on the end of the rocker arm is over the exact center of the valve stem when the rocker arm is at the halfway point of its maximum lift. It's also important to make sure all the valve stems are installed at the same height so the same length pushrod can be used for every cylinder. If valve heights vary, each pushrod will have to be measured individually for each valve.

With pushrods that have balls at both ends, the length can be the overall length of the pushrod end-to-end, or it can be the "theoretical length" of the pushrod (which is measured as if the oil holes were not in the balls). Determining the theoretical length requires using a special gauge that compensates for the oil hole, or estimating how much the oil hole reduces the radius at each end of the pushrod.

With pushrods that have a cup at the top end, the overall length can be measured end-to-end, or you can use the "effective length" which is the overall length of the pushrod minus the depth of the cup on the one end. This can be done by placing a ball in the cup, measuring the overall length of the pushrod with the ball in place, then subtracting the diameter of the ball.

Whatever method you use, make sure your pushrod supplier knows how you are measuring pushrod length so you can get the correct length pushrods from them. You may also need to discuss spring pressure and rocker arm ratio to determine how much stiffness is needed to handle the load.

Lifter Lowdown
Flat tappet lifer technology hasn't changed much in recent years, but there is more interest lately in friction-reducing coatings to minimize the risk of premature cam failure. Nitriding adds hardness and wear resistance to the lifters.

One of the biggest issues engine builders say they have found with some flat bottom lifters is a poor finish on the bottom of the lifter. The finish may be too rough, not hard enough, or not have the right amount of convex to rotate the lifter. Flat lifters are not really flat on the bottom but have a slight taper, which can be seen by placing them on a flat surface and rocking the lifter slightly side to side.

One of the keys to getting proper lifter rotation is to make sure the lifter bores are properly aligned with the lobes on the camshaft. One supplier has recently introduced a new scribing tool that can help engine builders accurately determine lifter alignment. The tool has a pointed nylon scribe on the bottom that leaves a slight mark on the cam lobe. The cam can then be pulled out to see where the center of the lifter is in relation to the cam lobe. Ideally, the center of the lifter should be about 20% "uphill" from the center of the tapered lobe for optimum rotation. If the lifter is on the low side of the lobe center, it won't rotate and will probably wipe out the cam lobe causing premature cam failure. A shim kit that installs behind the cam gear can be used to reposition the cam forward or backwards in the block to correct any misalignment with the lifters.

Another concern with flat bottom lifters is getting enough lubrication to the cam lobes. Splash lubrication may be okay for a low rpm stock engine with stock valve springs, but in a high revving engine with stiff valve springs, there's a lot of pressure between the lifters and cam lobes. By cutting a small "dribble" groove in the lifter bores, oil can dribble down and help lubricate the cam lobes. One aftermarket lifter supplier also sells a lifter that has a small hole in the face that helps lubricate the cam.

With few exceptions, most late model pushrod engines use roller lifters instead of flat bottom lifters. Roller lifters provide a significant reduction in friction, and also allow steeper lobes and faster valve opening and closing rates than flat bottom lifters. What's more, roller lifters reduce cam wear to the point where the cams just don't wear out, unlike cast iron, flat lifter cams that often round off lobes. The tradeoffs, though, are higher cost, more weight and an increased risk of lifter failure due to failure of the roller bearings.

The most critical area in a roller lifter is the roller bearing. If the needle bearings are not perfectly matched in size, the largest one will bear most of the load and eventually fail. One supplier said it sizes its needle bearings to the nearest micron and carefully matches all the needle bearings to improve the durability of its roller lifters.

Solid Or Hydraulic Lifters?
Hydraulic lifters, either flat bottom or roller, are fine for street engines that don't rev much higher than 6,000 rpm. Above a certain point, the lifter can't handle the spring pressure and collapses. On the other hand, hydraulic lifters are nice for street engines because they use oil pressure to maintain valve lash. This keeps the engine quiet and eliminates the need for constant lash adjustments.

Solid lifters, either flat bottom or roller, are usually preferred for racing unless rules prohibit them. A solid lifter is rigid with no oil cavity or spring-loaded plunger under the pushrod. Because it has no "give" it can't take up valve lash and requires adjustments to the rocker arms to set the proper valve clearance. That makes for a noisy valvetrain, but also allows a racer to "tune" his engine by changing the lash adjustment for more or less valve lift and duration. A solid lifter can also handle as much rpm as the valve springs can withstand, so that's why most high revving pushrod engines use them.

As for rebuilders of stock engines, costs can be minimized by rebuilding rather than the original lifters. It's more economical to rebuild roller lifters than to replace them with new ones, but that's not the case with flat bottom lifters. New lifters can usually be purchased for less that what it would cost to rebuild them.

One supplier of remanufactured roller lifters said its customers have fewer problems with remanufactured lifters than it does with new lifters. There are serious quality issues with many lifters that are sourced off-shore. "There has been a great deal of upheaval in the lifter industry over the past four or five years," the supplier said. "A lot of people have learned the hard way that cheaper parts from overseas aren't necessarily the best parts to buy."

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Re: installing the cam & breaking in a new engine

Postby grumpyvette » May 2nd, 2011, 1:15 pm

one common problem I see many guys go thru is the result of not understanding what visual clues, or obvious symptoms indicate, when they see them.
when your breaking in a new engine or cam, one common problem indicator is the headers running excessively hot
these oils tested the best, Id strongly suggest the Valvoline racing oils as the best value

10W30 Lucas Racing Only, full synthetic = 106,505 psi
zinc = 2642 ppm
phos = 3489 ppm
moly = 1764 ppm

10W30 Valvoline NSL (Not Street Legal) Conventional Racing Oil = 103,846 psi
zinc = 1669 ppm
phos = 1518 ppm
moly = 784 ppm

10W30 Valvoline VR1 Conventional Racing Oil (silver bottle) = 103,505 psi
zinc = 1472 ppm
phos = 1544 ppm

10W30 Valvoline VR1 Synthetic Racing Oil, API SL (black bottle) = 101,139 psi
zinc = 1180 ppm
phos = 1112 ppm
moly = 162 ppm

30 wt Red Line Race Oil, full synthetic = 96,470 psi
zinc = 2207 ppm
phos = 2052 ppm
moly = 1235 ppm

10W30 Amsoil Z-Rod Oil, full synthetic = 95,360 psi
zinc = 1431 ppm
phos = 1441 ppm
moly = 52 ppm

10W30 Quaker State Defy, API SL (semi-synthetic) = 90,226 psi
zinc = 1221 ppm
phos = 955 ppm
moly = 99 ppm







due to the effective delay in the ignition process because the ignition is not advancing to compensate for the lower time frame between ignition and the power stroke as the rpms increase as the rpms increase a greater percentage of the fuel/air mix thats being burn exits the exhaust still burning, greatly increasing the exhaust temps in the heads and exhaust manifolds




viewtopic.php?f=70&t=3438 ... %20Nov.pdf


btw notice the front header tube seems to be a bit cooler and each header tube as you move to the rear looks a bit hotter, thats because the engine compartment air flow cools the headers less effectively as its heated as it moves from the radiator rear ward

the picture above is commonly the result of having Your ignition timing too retarded for the 2500rpm-3500rpm your supposed to be lapping a new cam in at for the first few minutes,or the ignition advance curve rpm is to slow with a light load. Under a light load combustion is a slower process. Some of the combustion is still taking place after the exhaust valve opens which will make the headers glow.
if your running a LEAN due to either jetting, tuning issues or a large vacuum leak....the overly lean fuel/air mix tends to raise the exhaust temps, obviously an IR temp gun can be very useful in spotting this condition early, but its even more useful because it can easily tell you if only one or two headers are running significantly hotter, usually indicating a vacuum leak or tuning issue rather than ignition timing where all the header tubes tend to run hot.
now obviously you should have verified the correct oil and coolant levels and verified your ignition timing and advance and firing order before starting it , or seeing the headers glow before letting the engine run very long

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