Wesco Valve and Manufacturing Company provides quality power engine valves for almost any application. Even though dimensional conformity to the latest available O.E.M. prints is strictly enforced, Wesco has found it necessary to offer a variety of material content to accomodate many different conditions that affect engine valve life and performance.
Power valves in a four-stroke cycle engine are used to admit fuel and air into the combustion chamber and release burnt gases after combustion. They are used in conjunction with the rest of the valve train to do this at precisely the correct time to allow efficient operation, and at the same time, seal the intake and exhaust ports during combustion.
Proper selection of materials for spark and compression ignition engine exhaust valves depends on four major factors:
Operating temperature is the most critical. An increase in temperature will cause a reduction in the mechanical properties and an increase in the corrosion rates of valve alloys.
Total stress state -- including thermal and cyclic stress effects -- dictates the strength, fatigue, and creep properties a valve must have at a given operating temperature.
Because the exhaust valve functions as a high-temperature gas seal, the corrosivity of exhaust gases and the abrasiveness of solid combustion residues influence the types of corrosive attack and wear an exhaust valve must withstand. Critical contacting interfaces are as follows: The valve face/cylinder head, valve stem/valve guide, and valve tip/rocker arm. Excessive wear at any of these locations can cause valve failure.
4140 stem, 21-12N head
Our standard engine valve is made from a 21-12N stainless steel head, which is inertia-welded to a 4140 stem. The valve stem is chrome-plated to extend stem and guide life, and the tip is flame-hardened. The 21-12N valve head has a hardness of about 22 Rockwell, making this a suitable O.E.M. replacement valve for most applications.
4140 stem, 21-12N head with Stellite® #6 inlaid on seating area of valve
Our premium valve consists of the same base materials as our standard valve, 21-12N head and 4140 chrome-plated stem. An overlay of Stellite® #6 is applied to the entire width of the seating surface at a minimum depth of 1/16", providing additional hardness (37 Rockwell) and extending life in the most critical contact area of the valve.
4140 stem, 21-12N head with Tribaloy® inlaid on seating area of valve -- takes less oil to reduce wear; for clean or lean burn engines
For Clean/Lean Burn Engines Tribaloy® 400 is an intermetallic material with outstanding resistance to wear, galling and corrosion over wide temperature ranges. This material is ideal for minimum lubricated wear situations.
Tribaloy® structure consists of intermetallic materials of hard, intermetallic (laves) phase dispersed in a softer matrix of eutectic or solid solution.
Environments where Tribaloy® alloys have shown exceptional performance include but are not limited to:
Tribaloy® intermetallic materials maintain unique surface properties over a wide range. They exhibit outstanding resistance to wear and galling, high corrosion resistance and are particularly suitable where lubrication is a problem.
Tribaloy® is particularly recommended in applications involving low lubricity and corrosive gases. Typical application would include clean/lean burn engines.
Wesco Valve has been an industry leader in the application of Tribaloy® hardfacings for many years and has had vast experience in solving severe service application needs.
4140 stem, inconel head, used in extremely high heat service
In a highly corrosive fuel environment, base materials which resist corrosion and oxidation are required. For these applications, the valve head is forged from Inconel® 751, using the same 4140 chrome-plated stem material. The Inconel® valve head is hardened to approximately 38 Rockwell, and provides excellent wear life in this type environment.