Valve train points to check
From Crankshaft Coalition Wiki
(→Areas of the valve train that need to be checked and verified: add text, links; clean up) |
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[[File:Valvetrain selection parts.jpg|thumb|440px|Selection of various valve train components]] | [[File:Valvetrain selection parts.jpg|thumb|440px|Selection of various valve train components]] | ||
==Overview== | ==Overview== | ||
| − | The valve train is one of the most important segments of any engine build. | + | The valve train is one of the most important segments of any engine build. Obviously there can be no destructive contact/collision between any part of the reciprocating assembly or engine castings and the valve train. Besides avoiding physical contact, there are also minimum and maximum clearances that have to be established and checked to be sufficient. |
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==Things that affect valve train clearances== | ==Things that affect valve train clearances== | ||
Many things can affect valve train clearances. When an engine is rebuilt or modified, often the block and/or cylinder heads will be milled to provide a flat surface with the correct finish for the head gasket to seal. If a different lift camshaft is installed, or if a different design or ratio rocker arm is used, or different length valves, resurfacing the valve and seats, different compressed thickness head gasket, changes to the stud boss height and/or installing guide plates or different design studs, lifter having a different measurement between the foot or roller and the pushrod cup, changes to valve spring installed height or diameter, or spring retainer and/or lock type, and different pushrod length all can change the clearances and geometry of the valve train. So if any of these things have been altered, the valve train clearance points need to be checked and verified to be correct. Manufacturing and tolerance stacking and wear can all change the exact measurements, so these things should be physically measured rather than figured using published figures. | Many things can affect valve train clearances. When an engine is rebuilt or modified, often the block and/or cylinder heads will be milled to provide a flat surface with the correct finish for the head gasket to seal. If a different lift camshaft is installed, or if a different design or ratio rocker arm is used, or different length valves, resurfacing the valve and seats, different compressed thickness head gasket, changes to the stud boss height and/or installing guide plates or different design studs, lifter having a different measurement between the foot or roller and the pushrod cup, changes to valve spring installed height or diameter, or spring retainer and/or lock type, and different pushrod length all can change the clearances and geometry of the valve train. So if any of these things have been altered, the valve train clearance points need to be checked and verified to be correct. Manufacturing and tolerance stacking and wear can all change the exact measurements, so these things should be physically measured rather than figured using published figures. | ||
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==Areas of the valve train that need to be checked and verified== | ==Areas of the valve train that need to be checked and verified== | ||
This list is not all-inclusive. Not all areas will apply to all engines and/or builds.<br> {{Note1}}There is no substitute for physically measuring critical areas like piston-to-valve clearances or valve spring installed height and coil bind. For those measurements, do not rely solely on published figures.[[File:Spring clearance diagram1.jpg|thumb|upright=3|Valve spring clearances. Seal to retainer may be less in some cases]] | This list is not all-inclusive. Not all areas will apply to all engines and/or builds.<br> {{Note1}}There is no substitute for physically measuring critical areas like piston-to-valve clearances or valve spring installed height and coil bind. For those measurements, do not rely solely on published figures.[[File:Spring clearance diagram1.jpg|thumb|upright=3|Valve spring clearances. Seal to retainer may be less in some cases]] | ||
| − | *[[Valve spring | + | *'''[[Valve spring tech|Valve spring specs]]''' |
| − | *[[Valve train points to check#Valve train geometry|Correct geometry]] | + | **Valve spring rate |
| − | + | **Installed height | |
| + | **Coil bind | ||
| + | *[[Valve train points to check#Valve train geometry|'''Correct geometry''']] | ||
*Retainer to seal/valve guide boss at full lift | *Retainer to seal/valve guide boss at full lift | ||
*Retainer to rocker | *Retainer to rocker | ||
*Rocker trunnion (roller rockers) or pivot ball/rocker body (stamped steel rockers) to stud boss | *Rocker trunnion (roller rockers) or pivot ball/rocker body (stamped steel rockers) to stud boss | ||
| − | *Piston-to-valve clearance (both before and after TDC on overlap). Also see [[Quench]] | + | *[[Media:P to v rhs.pdf|'''Piston-to-valve clearance''']] (both before and after TDC on overlap) |
| + | **When advancing/retarding the cam, be sure to recheck piston to valve clearance. Each degree of change effects valve clearance approximately 0.010". Example: If you advance the camshaft 4 degrees, you will '''lose''' about 0.040" clearance between the intake valve and piston, and you will ''gain'' about 0.040" clearance between the exhaust valve and piston. It will be the opposite if the camshaft is retarded. | ||
| + | **Also see '''[[Quench]]''' | ||
*Push rod to guide slot in head (see image below) | *Push rod to guide slot in head (see image below) | ||
| − | *Use '''EITHER''' self-aligning rockers '''OR''' pushrod guide slots in head '''OR''' guide plates, | + | *Use '''EITHER''' self-aligning rockers '''OR''' pushrod guide slots in head '''OR''' guide plates, but ''NEVER'' two or more of these at the same time |
*"Rails" of self aligning rockers to retainer and/or locks | *"Rails" of self aligning rockers to retainer and/or locks | ||
*Rocker to valve tip (if needed, adjust guide plates if used) | *Rocker to valve tip (if needed, adjust guide plates if used) | ||
*Rocker slot to stud (if using stamped rockers w/pivot balls) | *Rocker slot to stud (if using stamped rockers w/pivot balls) | ||
| − | *Rocker arm/ | + | *Rocker arm/polylock to valve cover or oil baffle |
*Camshaft endplay | *Camshaft endplay | ||
*Distributor shaft endplay and distributor/cam gear mesh/alignment | *Distributor shaft endplay and distributor/cam gear mesh/alignment | ||
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*Hydraulic lifter preload or solid lifter lash setting | *Hydraulic lifter preload or solid lifter lash setting | ||
*Timing set phasing | *Timing set phasing | ||
| − | *[[Timing tabs and damper TDC lines SBC]] | + | *'''[[Timing tabs and damper TDC lines SBC]]''' |
*Cam gear to crank gear alignment | *Cam gear to crank gear alignment | ||
*Cam gear end play if roller cam | *Cam gear end play if roller cam | ||
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*Timing set to timing gear cover | *Timing set to timing gear cover | ||
*If using the SBC OEM roller cam, lifters and retainers, the '''lobe lift''' must be kept below 0.354” so the lifter won’t lose contact with the retainers | *If using the SBC OEM roller cam, lifters and retainers, the '''lobe lift''' must be kept below 0.354” so the lifter won’t lose contact with the retainers | ||
| − | *Cam lobe to connecting rod bolt on | + | *Cam lobe to connecting rod bolt on stroker engines |
[[File:Sbc prod guide slot.jpg|thumb|left|450px|Red arrows indicate the pushrod guide slot; slot needs elongating towards the rocker stud if 1.6 ratio rockers are used]]<br style="clear:both"/> | [[File:Sbc prod guide slot.jpg|thumb|left|450px|Red arrows indicate the pushrod guide slot; slot needs elongating towards the rocker stud if 1.6 ratio rockers are used]]<br style="clear:both"/> | ||
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==References== | ==References== | ||
;Crankshaft Coalition wiki articles | ;Crankshaft Coalition wiki articles | ||
| − | *[[Valve spring | + | *[[Valve spring tech]] |
*[http://www.crankshaftcoalition.com/wiki/Camshaft_install_tips_and_tricks Cam installation tips/tricks] | *[http://www.crankshaftcoalition.com/wiki/Camshaft_install_tips_and_tricks Cam installation tips/tricks] | ||
*[http://www.crankshaftcoalition.com/wiki/Adjusting_hydraulic_lifters Adjusting hydraulic lifters] | *[http://www.crankshaftcoalition.com/wiki/Adjusting_hydraulic_lifters Adjusting hydraulic lifters] | ||
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