Editing Valve train geometry
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==Overview== | ==Overview== | ||
Valve train geometry is an important aspect of building a performance engine. If done correctly, having the correct geometry will increase power and reliability. | Valve train geometry is an important aspect of building a performance engine. If done correctly, having the correct geometry will increase power and reliability. | ||
==Measuring a pushrod== | ==Measuring a pushrod== | ||
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Overall or "actual" length doesn't always equate to the pushrod length as specified by the manufacturer, odd as this sounds. The difference is in whether the pushrod was measured by overall or actual length (longest measurement of the three), "theoretical" length (about 0.020" longer than actual length) or "gauge" length (longest of the three). | Overall or "actual" length doesn't always equate to the pushrod length as specified by the manufacturer, odd as this sounds. The difference is in whether the pushrod was measured by overall or actual length (longest measurement of the three), "theoretical" length (about 0.020" longer than actual length) or "gauge" length (longest of the three). | ||
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The gauge length is what Comp Cams (as an example) uses. This is measured as how the pushrod sits in the rocker arm and lifter seats. In the Comp Cams diagram below, 8" is just used as an example: | The gauge length is what Comp Cams (as an example) uses. This is measured as how the pushrod sits in the rocker arm and lifter seats. In the Comp Cams diagram below, 8" is just used as an example: | ||
− | To accurately judge the geometry, the hydraulic lifter either needs to be pumped up, or made solid, or a solid lifter w/the same seat height substituted to judge the geometry. | + | [img]http://www.thedirtforum.com/Diagram%20B-Pushrod%20Length.jpg[/img] |
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+ | The acid test is what the geometry looks like. To accurately judge the geometry, the hydraulic lifter either needs to be pumped up, or made solid, or a solid lifter w/the same seat height substituted to judge the geometry. | ||
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+ | A page on checking geometry- [url]http://www.lunatipower.com/Tech/Valvetrain/HowToVerifyValvetrainGeometry.aspx[/url] | ||
[[File:P rod length.jpg]] | [[File:P rod length.jpg]] | ||
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===Chevy small block=== | ===Chevy small block=== | ||
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*Stock hydraulic flat tappet SBC- 7.8” | *Stock hydraulic flat tappet SBC- 7.8” | ||
− | *SBC OEM hydraulic roller pushrods are 7.2” long. When using shorter | + | *SBC OEM hydraulic roller pushrods are 7.2” long. When using shorter V6 or L4 OEM roller lifters, start with 7.500" pushrods. |
*Crane retro hydraulic roller- 7.046" | *Crane retro hydraulic roller- 7.046" | ||
*Retrofit roller lifter pushrods are 7.300". | *Retrofit roller lifter pushrods are 7.300". | ||
===Pontiac V8=== | ===Pontiac V8=== | ||
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− | ==Things that can | + | Stock pushrod length- 9.130". If using Chevy lifters- 9.290”. |
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+ | ==Things that can effect pushrod length== | ||
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A large number of variables are involved in determining the correct length pushrod for your application. Pushrod length is affected by any of the following: | A large number of variables are involved in determining the correct length pushrod for your application. Pushrod length is affected by any of the following: | ||
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==Mid lift theory of valve train geometry== | ==Mid lift theory of valve train geometry== | ||
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− | + | Link to the [[http://www.aera.org/ep/downloads/ep10/EP04-2010_20-30.pdf Miller Mid-Lift ]] and rocker geometry article in the AERA (Automotive Engine Rebuilders Association) quarterly magazine '''''Engine Professional'''''. | |
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==Tools== | ==Tools== | ||
− | [[File:PUSH ROD LENGTH CHECKING TOOL | + | [[File:PUSH ROD LENGTH CHECKING TOOL 002.jpg|thumb|left|200px|Homemade adjustable pushrod length checking tool]] |
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+ | [[Category:undeveloped articles]] | ||
[[Category:Engine]] | [[Category:Engine]] | ||
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