Valve adjustment SBC/BBC

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If you can follow these instructions, the valves will be adjusted properly and the ignition timed and ready to start. Be sure if the engine is newly assembled or has sat for an extended period of time that the oil system is first primed before starting the engine.
 
If you can follow these instructions, the valves will be adjusted properly and the ignition timed and ready to start. Be sure if the engine is newly assembled or has sat for an extended period of time that the oil system is first primed before starting the engine.
  
==Alternative view/terminology==
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======Alternative view/terminology======
As with any single "center camshaft" engine that is fitted with hydraulic cam followers or "lifters", we are not actually adjusting valves. The term "adjusting valves" is a carry-over from the old days when mechanical valve operation was common. For these, there was an actual valve tip-to-follower clearance adjustment that was required.    
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<font size="1">NOTE:  As with any single "center camshaft" engine (that is fitted with Hydraulic Cam Followers [aka lifters]), we are NOT actually adjusting valves. The term "adjusting valves" is a carry-over from the old days when mechanical valve operation was common. For these, there was an actual valve stem-to-follower clearance adjustment that was required.
  
With hydraulic (originally called "self adjusting") lifters in an OHV engine, we are adjusting the lifter preload to position the lifter plunger within the lifter body. The goal is to set the plunger at the prescribed position within the lifter body.
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With Hydraulic Cam Followers (originally coined "self adjusting"), we are adjusting the rocker arm stud nut height as to change the push rod geometry as to positon the cam follower plunger "depth" within the cam follower body.  
Many hydraulic lifter plungers will have a hydraulic functioning range of around 0.100" or so- but this is not the the case in all lifters, so this must be verified for the particular lifter being used.  
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Many hydraulic plungers will have a hydraulic functioning range of around .100" or so.
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The goal is to set the plunger at it's OEM prescribed depth within the follower body.
  
[http://www.youtube.com/watch?v=lorANZ1Tptw '''Here'''] is a video that shows an animation of a hydraulic lifter in operation.
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Here is an image that shows a cam follower as it becomes hydraulically active. Note the plunger and it's travel within the follower body.  
  
The lifter preload adjustment can be done statically (engine off) or dynamically (engine running). When this adjustment is done statically, some recommend that the crankshaft be stopped in as many "stops" as there are cylinders. In other words for a V8 engine, use 8 stops beginning with #1 cylinder @ TDC of the compression stroke, continuing following the engine's firing order) and not the 2 or 3 stop procedure that is sometimes recommended.
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http://www.youtube.com/watch?v=lorANZ1Tptw
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This adjustment can be done statically or dynamically.  
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When this initial adjustment is done statically, I highly recommend that we stop the crankshaft in as many "stops" as there are cylinders. IOW, for a V-8 engine, we use the 8 stop procedure, beginning with #1 cylinder @ TDC C/S (right down the engine's firing order)..... not the 2 or 3 stop procedure that is sometimes recommended.
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==Also see==
 
==Also see==
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*[[How to make a timing tape]]
 
*[[How to make a timing tape]]
 
*[[Camshaft install tips and tricks]]
 
*[[Camshaft install tips and tricks]]
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*[[http://www.aera.org/ep/downloads/ep10/EP04-2010_20-30.pdf]]
  
 
[[Category:Engine]]
 
[[Category:Engine]]
 
[[Category:Adjust valves]]
 
[[Category:Adjust valves]]
 
[[Category:GM]]
 
[[Category:GM]]

Latest revision as of 15:58, 6 March 2014

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