What cam is right for me?
When people start looking at performance cams, the first mistake most people make is assuming that bigger is better. The best way to figure out what cam you need is to look at the desired rpm range. Also characteristics you want in your engine. Daily drivers, going with a cam that has a lot of duration will usually greatly decrease low rpm performance. Going with a short duration camshaft will usually create very good throttle response and low rpm performance. This will not allow adequate airflow at higher rpm for a really wide power band. Something in the middle is what is best for most people. It will allow you to have good throttle response at the lower rpm and a wide power curve that allows the engine to breathe at higher rpm. Moderate well rounded cams like these are best for most people. Examples of these would be the 188-220-109LSA for the Cummins and 192-200109LSA for the Duramax.
What to look for?
If you have an engine that is at or below 2,000rpm most of the time, there is a benefit in choosing a shorter duration camshaft that leaves the valve open less time after Bottom Dead Center of BDC. The longer the valve is open after bottom dead center, the more air that is pushed out of the cylinder, back into the intake runner. The shorter amount of time the intake valve is open after BDC, there is usually more air trapped in the cylinder at lower rpm. More power and efficiency potential can be achieved at low rpm. I say power potential because diesels, unlike their gasoline counterparts, only allow air into the cylinder, not air and fuel. The other reason I describe the effect as potential is that as long as more air is available in the cylinder for a given RPM, it is up to the injection system to get the right amount of fuel into the cylinder at the right time to take advantage of the additional air.
Daily Drivers – 178/208, 182/214, 188/220
Turbo size, application, and RPM range are important, look at each cams description to see if the would fit your application.
Drag strip – 194/220, 207/220, 214/240
Turbo size, application, Head work and RPM range are important, look at each cams description to see if the would fit your application.
Sled Pullers – 207/220 and up
Turbo size, application, Head work, injection rate and RPM range are important. Look at each cams description to see if the would fit your application.
Do I need a steel or cast camshaft?
The OEM Cummins camshaft is a chill-cast ductile iron material. Due to the chill-cast process it has a very hard surface that allows it to have a long life in the extreme environment in which operates. Though it has a very hard exterior, it has a somewhat softer core. Your vehicle can handle torsional forces without fracturing in a wide number of applications. Issues arise however when the cam that was designed for 200hp and 2,800 rpm starts getting pushed beyond 5,000rpm. Additional issues can arise when large injection pumps, heavy springs and high-lift profiles are used.
High-lift camshafts, heavy springs and large capacity injection pumps create cyclical torsional forces much greater than what the cam was designed to handle. In many cases the camshaft will fail between the nose and cylinder number 2. Also between the nose and whichever journal pushed through the hydrodynamic film of oil. A steel camshaft will stop most all breakage due to torsional harmonics, but is still vulnerable to breakage due to journal seizure. The Cummins B, ISB and ISBE engines, depending on CPL, have either one or two bearings for the seven journals. The other five or six journals ride directly on the block. Where big lift cams and high spring pressure are used, the cam can push through the oil film that separates the cam and block and seize. Having the block line-bored and installing journal bushings will ensure this does not happen.
If you are running a cam with more than 210 degrees of duration @.050″, more than .340″ lobe lift more than 420# nose pressure or getting close to 5,000rpm there is a benefit with having your block modified to accept cam journal bearings.
If you are running close to or exceeding 5,000rpm or have a 13mm p-pump, then you are a good candidate for a steel camshaft.
How should I break in my new camshaft
The first 5 minutes of operation of your new camshaft is very important. Ninety percent of all issues arise in this period and have to do with inadequate lubrication.
To make sure that you have no issues during break-in, follow these few suggestions.
– Make sure that the cam has a Liberal amount of quality assembly lube applied
-DO NOT let the engine start without oil pressure
– When this is a new engine, be sure to put a liberal amount of assembly lube in the oil pump and prime the oil filter
– Be sure to change the oil after you have done your break-in procedure. When the filter and oil system are already primed, engine will get oil pressure much faster than if the oil is changed at the same time.
-Disconnect the fuel system and spin the engine with the starter until oil pressure can be read or until oil is coming out of the rocker arms.
-Do not let the starter run for more than 10 seconds at a time
– Once oil pressure has been verified, let the engine start and run for five minutes at 1200-1500rpm then shut engine down
-Adjust valves then you are cleared to abuse your engine. Enjoy the added airflow
-if you need to re-torque or “hot-torque “the head, do so before adjusting valves. Re-torqueing the head changes the valve lash setting, so it is important to set lash last.
2-3 times a year I get calls from customers that have lash starting to get loose on the last 3 cylinders. This is caused from poor lubrication at the time of initial start-up. In this case the cam literally eats its way through the block away from the force of the tappets. Assembly lube and oil pressure on start-up are a pretty big deal to your cam. Don’t let this happen to you.
How do I change my installed centerline?
In most instances our cams do not need to have the centerlines moved. Our cams are ground on a CNC grinder to ensure that each cam is on the correct centerline. There is a +/- specification that Cummins uses during manufacture of the crank and cam gears. Usually there is less than 1 degree of variation from engine to engine and in rare instances 2+ degrees. Issues arise when people start to switch crankshafts and cam gears from different engines and year models. Creating an instance where the cam might be installed on a centerline that might allow piston to valve clearance or performance issues. To remedy incorrect camshaft installed centerline, call our office and order an offset key. We have keys that will offset the cam centerline from 1.5-5degrees.