Camshaft Technology: What is the Nitriding Process?
Ever since we first realized that putting a bunch of lead into the air wasn’t such a great idea back in the late 60’s, there’s been an ongoing struggle between efforts to protect the environment and the quest for more speed. The most recent concern has been the reduction of key constituents in motor oils which are essential for flat tappet cams and lifters to prevent premature wear and failure. In response to the problem, COMP Cams’ patented Pro Plasma nitriding process fills the void created by the phase-out of these chemicals, providing durability in these essential components.
Where’s the problem?
Recently, racers using flat tappet cams have been experiencing severe problems with extreme wear and failure in their cams and lifters. More cams have had lobes wiped in the past couple of years than the previous 20 years combined. Ok, that might be a little bit of an exaggeration, but having experienced a lobe wiping incident personally, and watching other racers experiencing similar camshaft problems, an explanation was in order.
Camshafts that had wiped lobes left racers wondering “what went wrong?”
Almost immediately, finger pointing began. Racers were blaming “offshore” and “brown box” lifters. It seemed that everyone had an opinion on why camshafts and lifters were failing at an alarming rate. Then news starting coming out from the most unlikely sources. Petroleum engineers recognized the problem long before us grassroots racers did.
Lifters were “dished” in a matter of minutes without the proper chemical protection.
As we were experiencing component failures, the engineers were already at work on the problem. It seemed that ever-tightening EPA regulatory mandates required that key chemicals that control wear, phosphorous and zinc, were greatly reduced in conventional motor oil formulation. Zinc and phosphorous are combined to make the anti-wear chemical zinc dialkyl dithiophosphate (ZDDP), and over the past 18 months, the American Petroleum Institute’s (API) standard that regulated the reduction of ZDDP in motor oil has been discussed thoroughly in industry magazines and enthusiasts’ online forums.
This is the COMP Cams Pro Plasma Nitriding System in all it’s glory.
What’s the fix?
ZDDP worked by continuously coating the camshaft with a thin layer to keep some separation between the metal parts. Initially, other more environmentally-friendly chemicals were studied as suitable replacements for ZDDP.
When alternatives proved too expensive or impractical, the search for a solution turned to alternative manufacturing processes to shore up the components themselves. COMP Cams, a leader in valve train technology, has come up with a process that deals with flat tappet durability concerns by pioneering the use of pulse plasma nitriding of valve train components.
How Pulse Plasma Nitriding Works
Nitriding is basically a surface hardening treatment. Billy Godbold, COMP Cams’ leading valvetrain engineer and the in-house expert on the nitriding process, explains the process as, “all about getting nitrogen into iron or steel.” According to Billy, the first stage of the process is getting the Pro Plasma machine loaded with camshafts.
The gasses used in the Pulse Plasma Nitriding process.
Once it is loaded, the cover is placed over the machine and virtually all the air is removed from the interior of the machine’s sealed chamber, creating a near-total vacuum. The interior is then filled with pure nitrogen and the newly-created atmosphere is charged. This creates a nitrogen plasma that infuses nitrogen ions into the parts, fortifying them on a molecular level.
Camshafts loaded into the machine, ready for nitriding.
Depending on the speed and makeup of these nitrogen ions, some of them penetrate as far as .010-inches deep into the cam, while others bond themselves into the surface strata. The process creates three separate layers during the process. The deep layer, which provides strength against metal fatigue, is called the diffusion zone. A middle layer, called the compound zone, guards against abrasion and increases strength, while the surface layer affects the initial wear-in behavior of the cam, and gains lubricity from the nitriding process.
What makes the COMP Cams nitriding system special is the careful manipulation of the part’s microstructure by controlling the gasses introduced into the environment, the electrical charge in the atmosphere, and the exposure time throughout the entire 36-hour process. Thanks to this careful oversight, the treatment is reproducible, providing the same exact treatment every time.
The Advantage of Nitriding
Both the performance and the working lifespan of the camshaft are enhanced by the nitriding process. The nitrided part comes ready for use – it calls for no machining, polishing, or any other post-nitriding operations. There are no dimensional changes, distortion, or surface finish alterations, and the fatigue strength of the part is improved.
Cleaning the nitrided cams at the end of the process.
Billy Godbold explained that getting your cam nitrided is insurance against premature lobe wear, lifter seizure or even complete failure of the camshaft. COMP Cams Pro Plasma nitriding treatment is a permanent solution for flat tappet issues. It not only strengthens the contact area between the camshaft lobe and lifter, but also increases the surface lubricity through reduced friction. Pro Plasma nitriding is available as an added service for all COMP Cams® flat tappet camshafts.
Break-in Without Heartbreak
Though the Pro Plasma nitriding process greatly improves the durability and wear resistance of a treated camshaft, it’s no substitute for proper flat tappet camshaft break-in. Doing it right will allow the lifters to immediately develop the proper wear pattern and establish rotation, which will lead to a long, happy life for your new bumpstick. Here are some tips for proper camshaft break-in:
• Parts Selection
It goes without saying that you should never re-use flat tappet lifters with a new cam, but the quality of your new parts is just as important – COMP recommends their own lifters with cam face oiling provisions, rather than no-name generic parts of unknown origin and durability. The money you might save will be a small consolation when you’re taking the motor apart again and replacing the cam. AMC, Chrysler, and GM engine builders can also take advantage of COMP’s lifter bore grooving tools to increase oiling capacity.
Double-check your camshaft and lifter setup before you button everything up, and use plenty of the supplied assembly lube on all cam lobes, the distributor gear, and the bottom face of each lifter. Fill the engine with high-lubricity, high-ZDDP content engine oil, and a break-in additive. ROUSH Performanceoffers a SAE 40 conventional oil with high zinc content specifically for engine break-in, and Red Line Oilmakes a break-in additive that will treat up to 12 quarts of oil with a single bottle.
Purists using COMP parts can ‘keep it in the family’ with the company’s own COMP Cams Camshaft Break-In Oil Additive. If you’re using high-pressure dual valvesprings, remove the inner spring from each assembly for the break-in process. If you’re using stiff singles, COMP offers low-ratio rocker arms specifically designed for cam break-in to give an additional margin of safety. Either alternative will mean swapping parts on the head after break-in is complete, but it still beats a wiped lobe any day of the week.
Camshaft Break In Oil Additive.
As soon as the engine fires, make sure that the oil pressure comes up properly, then bring the revs up to 2,000-2,500 for the first 30 minutes. Running it slower won’t provide sufficient oil flow to the lifters and camshaft, and faster puts additional unnecessary stress on them during this critical process.
Varying the engine’s RPM within this range during the break-in period will help to direct oil splash lubrication to different areas of the camshaft – this can be especially important in engines with a windage tray or other measures to help control oil within the crankcase, so it’s worth the extra effort. After a half-hour, the engine oil and filter should be changed (turn it off first!) to remove contaminants and break-in lube. If you followed COMP’s suggestion and removed the inner valvesprings or installed low-ratio rockers for the break-in process, now’s the time to swap back to your regular setup.