| smokeonthewater |
05-27-2013 09:38 PM |
interesting article
http://www.enginebuildermag.com/Arti...echnology.aspx
"Improved lifter designs can also reduce the risk of lobe wear and cam failure. Some companies now make lifters that have a small pin hole in the bottom of the lifter to feed oil directly to the lobe. The hole may be centered over the lobe or offset slightly to one side. Another trick that can improve cam lubrication is to cut a small slot in each lifter bore so oil can drip down directly onto the cam lobes.
Cam Treatments
Another way to reduce cam lobe wear is to have the camshaft nitrided. Nitriding is a process where the camshaft is baked inside a sealed chamber at high temperature while being exposed to a pure nitrogen atmosphere. As the nitrogen diffuses into the surface of the iron, it forms a hard layer a few thousandths of an inch deep that improves wear resistance. It***8217;s not a coating and does not change the dimensions of the camshaft.
Some cam manufacturers offer nitriding as an option. The treatment costs about $100, and increases the surface hardness of the cam to about Rockwell 55 to 60. Some say the bottoms of the lifters should also be nitrided, but others say if the cam lobes and lifters are the same hardness it may increase the risk of galling during break-in.
Some cam suppliers use a process called ***8220;Parkerizing***8221; that applies an acidic lubricant to the outer surface of the cam to protect against galling during break-in. It***8217;s a temporary treatment and does not change the hardness of the cam.
Another way to reduce cam wear issues is to use an iron alloy that contains more nickel, or to go with a billet steel cam (both of which are more expensive than cast iron). Chase Knight of Crane Cams said his company is now using an upgraded camshaft material that is about three points harder than a standard cast iron alloy. Crane also offers a micropolished surface finish that reduces friction and improves the break-in process."
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