Editing Pistons and rings

==Overview==
Ring end gap clearance has to be checked and verified or severe engine damage can result. The following are general recommendations. Consult the manufacturer's instructions and use that if they vary from these recommendations.

End gap placement lets the engine start up without any gaps being aligned. Once the engine is in use, the ring end gaps change, this gives the best chance of them not aligning during use.

==Parts of a piston==

===Diagram===
[[File:Piston parts diagram.jpg|1000px]]

{| class="wikitable"
|-
! 1 to 10!! 11 to 20 !! 21 to 30
|-
|1. Compression Height ||11. Pin Oiler ||21. Skirt Thickness
|-
|2. Crown (Dome, Dish, Inverted Dome) ||12. Pin Span ||22. SS
|-
|3. Deck ||13. Pin Tower ||23. Support Band
|-
|4. Dome Angle ||14. Plug Relief ||24. Tang
|-
|5. Dome Diameter ||15. Ring Band ||25. Valve Relief (VR)
|-
|6. Dome Profile ||16. Ring Groove ||26. VR Angle
|-
|7. Dome Radius||17. Ring Land ||27. VR C/L Out 
|-
|8. Lock Groove ||18. Ring Root ||28. VR Depth
|-
|9. Oil Return ||19. Side Relief ||29. VR Diameter 
|-
|10. Pin Bore||20. Skirt ||30. VR Stop
|}

==Ring end gap clearances==
Unless otherwise instructed by the ring or piston manufacturer, a safe ring end gap clearance is:

===Top ring===
*0.0045" per inch of bore diameter for street/strip
*0.0050" for drag or road race
*0.0055" for supercharged or nitrous use
{{Warning|Be aware that there are pistons like some made by Keith Black that use a wider top ring gap than what is normally recommended by ring manufacturers or other piston manufacturers. So be sure to check and follow the '''piston''' manufacturer's instructions, if they differ from the ring manufacturer's instructions.}}

===Second ring===
*The second ring should be gapped 0.004" to 0.008" wider than the top ring

===Oil ring===
*Minimum of 0.015" for the oil ring rails, do not file oil ring expander or rails 

==Ring gap examples==
===4 inch bore (SBC, SBF, etc.)===
*4.00" plus 0.030" overbore = 4.030" 
*4.030" bore X 0.0045" = 0.01612, or rounded off to 0.016" minimum end gap.

===4.125 inch bore (SBC 400, Pontiac 400, etc.)===
*4.125" plus 0.040" overbore = 4.165" 
*4.165" bore X 0.0045" = 0.0166, or rounded up to 0.017" minimum end gap. 

==How to square the ring in the bore==
Place a ring in the bore, then use a piston inserted upside down into the bore to square the ring.
 
==Ring end gap location==
The ring end gaps need to be located in such a way that they don't align. The rings tend to rotate on their own during the life of the engine, so starting them out as shown will prevent them from aligning, at least not right away.

While there are different thoughts on ring end gap placement, unless the manufacturer's instructions say otherwise, the following diagram will work fine:

[[File:PISTON RING END GAP LOCATION.jpg]]

[[Category:Engine]]