Rocker arms
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===Stamped steel=== | ===Stamped steel=== | ||
A mainstay of OEM engines. They're cheap to produce and perform adequately, although in serious competition and high performance applications they leave a lot to be desired. The ratio is often less than advertised, the ball pivot like used by Chevy and Pontiac are prone to wear and friction. | A mainstay of OEM engines. They're cheap to produce and perform adequately, although in serious competition and high performance applications they leave a lot to be desired. The ratio is often less than advertised, the ball pivot like used by Chevy and Pontiac are prone to wear and friction. | ||
| + | *http://www.cranecams.com/313.pdf | ||
===Roller tip=== | ===Roller tip=== | ||
The roller tip only rockers are mostly a gimmick. Their only real advantage comes not from the roller tip (which by one estimate would need to be a 2" diameter roller to duplicate a stamped steel rocker), but from the more accurate ratio; stock stamped steel rockers often have less than advertised ratios and this means less than advertised lift, and a good chance of less peak performance. | The roller tip only rockers are mostly a gimmick. Their only real advantage comes not from the roller tip (which by one estimate would need to be a 2" diameter roller to duplicate a stamped steel rocker), but from the more accurate ratio; stock stamped steel rockers often have less than advertised ratios and this means less than advertised lift, and a good chance of less peak performance. | ||
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| + | That said, the 1.52:1 advertised roller tip rockers are a lot more uniform and they can increase performance, primarily due to the increase in ratio- NOT because of the roller tip. | ||
===Roller trunnion=== | ===Roller trunnion=== | ||
| − | [[File:LS7 stock rocker arms.jpg|thumb|400px|Gen 3/4 Chevy rockers]]A roller trunnion is the best improvement that can be made to a rocker arm using a design that permits it. As an example, Chevy Gen 3 and 4 engines use a roller trunnion without a roller tip. These rockers are very efficient and represent the state of the art as far as OEM rocker arms go. These rockers can be upgraded with a replacement trunnion bearing assembly and are then good for high performance use beyond what the stock bearings could take. <br style="clear:both"/> | + | [[File:LS7 stock rocker arms.jpg|thumb|400px|Gen 3/4 Chevy rockers]]A roller trunnion is the best improvement that can be made to a rocker arm using a design that permits it. As an example, Chevy Gen 3 and 4 engines use a roller trunnion '''''without''''' a roller tip. These rockers are very efficient and represent the state of the art as far as OEM GM rocker arms go. These rockers can be upgraded with a replacement trunnion bearing assembly and are then good for high performance use beyond what the stock bearings could take. <br style="clear:both"/> |
===Full roller=== | ===Full roller=== | ||
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