Rocker arms
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==Overview== | ==Overview== | ||
The rocker arm is a fulcrum. Its job is to turn the cam lobe's circular rotation into an up and down movement. This is able to be done because the rocker has a pivot point or fulcrum that allows the cam lobe to open the valve. | The rocker arm is a fulcrum. Its job is to turn the cam lobe's circular rotation into an up and down movement. This is able to be done because the rocker has a pivot point or fulcrum that allows the cam lobe to open the valve. | ||
| − | The rocker arm's pivot point is not in the center of the rocker; instead it is offset more towards the pushrod. The amount of offset is expressed as a ratio (1.5, 1.6, 1.7, etc.) | + | The rocker arm's pivot point is not in the center of the rocker; instead it is offset more towards the pushrod. The amount of offset is expressed as a ratio (1.5, 1.6, 1.7, etc.). |
The stock small-block Chevy rocker arm has a 1.5:1 ratio. These rockers are called 1.5 ratio rockers or just 1.5 rockers for short. This means that the rocker arm tip at the valve end of the rocker moves 1.5 times the amount of movement seen at the pushrod end of the rocker- which is also the same amount as the camshaft's lobe lift. | The stock small-block Chevy rocker arm has a 1.5:1 ratio. These rockers are called 1.5 ratio rockers or just 1.5 rockers for short. This means that the rocker arm tip at the valve end of the rocker moves 1.5 times the amount of movement seen at the pushrod end of the rocker- which is also the same amount as the camshaft's lobe lift. | ||
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===Full roller=== | ===Full roller=== | ||
| − | Aftermarket rockers are available as full roller (tip ''and'' trunnion). The benefits are less friction and less oil needed to lubricate them. While these used to be considered high-end race-only parts, the price has dropped to the point where a set of decent full roller (tip and trunnion) can be had for not much more than a quality set of stamped steel rockers. | + | [[File:Jessel mohawk AFR ford windsor.jpg|thumb|400px|Jessel full roller rockers on a Ford Windsor engine]]Aftermarket rockers are available as full roller (tip ''and'' trunnion). The benefits are less friction and less oil needed to lubricate them. While these used to be considered high-end race-only parts, the price has dropped to the point where a set of decent full roller (tip and trunnion) can be had for not much more than a quality set of stamped steel rockers. |
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===Self aligning vs. non self aligning=== | ===Self aligning vs. non self aligning=== | ||
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[[File:Lewis tool in use.jpg|thumb|500px|Lewis tool being used on a SBC head]]A Lewis tool is used on SBC heads to lengthen the pushrod slot towards the rocker stud for use with increased ratio rocker arms. This can also be done by hand using a die grinder or even a rat tail file, but the Lewis tool makes short work of it by using the tool, a 5/16" drill bit and drill. <br style="clear:both"/> | [[File:Lewis tool in use.jpg|thumb|500px|Lewis tool being used on a SBC head]]A Lewis tool is used on SBC heads to lengthen the pushrod slot towards the rocker stud for use with increased ratio rocker arms. This can also be done by hand using a die grinder or even a rat tail file, but the Lewis tool makes short work of it by using the tool, a 5/16" drill bit and drill. <br style="clear:both"/> | ||
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[[Category:Engine]] | [[Category:Engine]] | ||
[[Category:Cylinder head]] | [[Category:Cylinder head]] | ||
[[Category:Undeveloped articles]] | [[Category:Undeveloped articles]] | ||
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