Editing Determining top dead center (section)
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==Piston stop== If the engine is a short block on the stand, you can determine TDC with a simple homemade piston stop made from a strap of metal bolted across two head bolt holes, with the strap drilled and tapped for an adjustable bolt/nut assembly. A dial indicator can also be used on a fixture that bridges the bore or on a magnetic base. This would be an ideal time to note the piston-to-deck clearance for use in computing the static compression ratio and quench distance. If the engine has the heads on, use a spark plug-type piston stop tool. If there is a timing tab present, use it to mark the position with. If no tab, use a length of stiff wire that's attached to the engine to use to show the positions. This may be made easier by using a degree wheel or a timing tape on the outer ring of the damper. #Set the plug hole-mounted piston stop to contact the piston close to TDC #Rotate engine until the stop just contacts the piston- mark the location #Then rotate in the opposite direction until the piston is stopped #Half way between the two marks is approximately TDC [[File:TDC1.jpg |thumb|left|Strap-type and spark plug-type piston stop tools]] <br style="clear: both" /> ===A word on using the damper retaining bolt to turn the engine over=== If the damper/balancer retaining bolt is used to turn the crank over, the bolt can loosen if turned CCW. If this happens the bolt will need to be retorqued (60 ft/lbs on a SBC, 85 ft/lbs on a BBC). Another risk is in stripping the threads or breaking the bolt off if you use the damper bolt to turn the engine over. If you feel resistance, or if the bolt tightens more as you attempt to turn the crankshaft- STOP! You will need to use a remote starter switch, or turn the damper by hand (plugs out), or turn the flexplate/flywheel from beneath the vehicle. The safest/easiest way to turn the crank is to use a tool that allows a large ratchet or breaker bar to be used. <gallery> File:Crank turning tool.jpg|Damper-mounted crank turning tool File:Crank turning tool2.jpg|Crank snout-mounted crank turning tool </gallery> <br style="clear: both" />
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