Proper Cam Break-In Procedure


Recent changes in oil and engine technology are likely the cause of premature camshaft failure; here’s how you can protect your engine!

Premature flat tappet camshaft failure has been on the rise recently and not just with one brand or type of camshaft. In almost every case, the hardness or the taper of the cam lobe is suspected, yet most of the time that is not the problem. This growing trend is due to factors that are completely unrelated to camshaft manufacture or quality control. Changes in today’s oil products and “advancements” in internal engine configurations have contributed to a harsher environment for the camshaft and increased the potential for failure during break-in. But there are several things you can do to curtail this discouraging trend.

Engine Building Tips & Parts Selection

Today’s engines are great at providing oil to every engine component except one – your camshaft. Windage trays limit oil’s ability to reach the top of the engine. Modifying connecting rod side clearances for less oil splash reduces the amount of oil that reaches the camshaft. Special oil pans further complicate both the break-in process and camshaft lubrication in general. While windage reduction frees up horsepower, special attention must be paid to ensuring proper supply of oil to the camshaft and lifters. By carefully selecting your engine components, you greatly reduce your chances of having a failure.

Lifter Selection

Flat-tappet lifters (solid/mechanical) with oiling holes in the cam face surface increases oil flow to the lifter-camshaft lobe contact point. Furthermore, using a lifter bore grooving tool (i.e. COMP Cams® #5003) will enhance oiling throughout the camshaft and valve train. As we all know, better oil flow means better initial break-in and increased camshaft durability. Additionally, make certain you purchase only high-quality lifters from reputable sources. Most lifters look alike, but you don’t really know where they were produced. “Imported” flat tappet lifters often times use inferior lifter castings and DO NOT deliver the proper durability and surface finish of high-quality, US-built lifters. Flat-tappet lifters must be built to strict diameter and radius tolerances and designed to fit precisely within their lifter bores to function properly in a high RPM engine. This ensures the lifter rotates properly and decreases the potential for failure. Additionally, flat tappet lifters must have the correct oil band depth and location to properly regulate the internal oiling of your engine.

Camshaft Nitriding

Nitriding is recognized by metallurgists worldwide as one of the most effective ways to increase the case hardness and lobe surface lubricity of flat tappet cams, all in an effort to enhance both break-in and long-term durability. Pro Plasma™ Nitriding is a patented process that uses pulsed nitrogen plasma to infuse nitrogen ions into the part – strengthening and fortifying the steel on a molecular level, to a depth of approximately .010 of an inch deep. COMP Cams® owns and operates a Pro Plasma™ Nitriding service in-house.


Engine Oil Selection

As we touched on earlier, another major factor in the increase of flat tappet camshaft failure is your favorite brand of engine oil. Simply put, today’s engine oil is just not the same as it used to be, thanks to ever tightening environmental regulations. The EPA has done a great job in reducing emissions and the effects of some of the ingredients found in traditional oils; however these changes to the oil have only made life tougher on your flat tappet camshaft. The lubricity of the oil and specifically the reduction of the important anti-wear additives such as zinc and phosphorus, which help break-in and overall camshaft life, have been drastically reduced. As stated in the book “Lubrication Fundamentals”,”In heavily loaded applications, flat tappet cam followers operate on partial oil films at least part of the time. Lubricants with anti-wear additives are necessary if rapid wear and surface distress are to be avoided. The oil additive Zinc Dithiophosphate is to provide anti-wear activity for the camshaft and lifters. With the increased use of roller follower cams (in production cars), the requirements for anti-wear have been changed to prolong the life of emission control devices.” The increased RPM and related increase in valve spring pressure in today’s racing engines require higher levels of formulated anti-wear, especially in flat tappet engines. Again, the book “Lubrication Fundamentals” sums this up, “Loading on the rubbing surfaces in the valve train may be high, particularly in high speed engines, where stiff valve springs must be used to ensure that the valves close rapidly and positively. This loading can result in lubrication failure unless special care is taken in the formulation of the lubricant.” Simply put, the oil used in a flat tappet engine needs to be formulated specifically for a flat tappet engine.

Proper Camshaft Break-In

Proper flat tappet camshaft set-up and break-in, as any engine builder knows, are keys to how long a camshaft will last, both short and long term. The correct procedure allows the lifters to establish rotation and develop a good wear pattern.

Break-In Preparation

Always remove the inner spring during break-in when using dual or high pressure valve springs. An alternative solution that addresses this same concern is using a set of low-ratio break-in rocker arms. Both of these solutions provide your best chance of proper camshaft break-in and long term durability. While these tips may be a slight inconvenience, a little time and effort on the front-end is much better than destroying your new engine.

Proper Procedure

As soon as the engine fires, bring the rpm up to 2000 to 2500 during the first 30 minutes of operation. Slower engine speeds will not supply the camshaft with an adequate amount of oil for the break-in period. The engine rpm may be varied periodically from 2000 to 2500 to direct oil splash to different areas of the camshaft. After the 30 minute break-in period, the inner valve springs should now be replaced and the correct rocker arms installed.