Pistons and rings

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{{Note1}} See the info at '''SBC oil ring depth''', below.

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==~~Ring~~ gap ~~examples~~==

+

==KB ring gap and piston to wall clearance instructions==

−

~~===4 inch bore~~ (~~SBC, SBF, etc.~~)~~===~~

+

{{Note1}}The following info is for the KB Icon/Icon FHR (Forged Head Relief) series and some KB hypereutectic pistons. Refer to manufacturer's instructions for other brands and types of pistons.

−

*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~~.~~)===~~

+

;[http://www.kb-silvolite.com/icon/clearance_pop.php Suggested Piston to Wall Clearance]<nowiki>:</nowiki>

−

*4.~~125" plus 0~~.~~040" overbore = 4~~.~~165"~~

+

KB pistons can be installed tighter than other performance pistons. A close fitting piston rocks less, supports the rings better and seals the engine for maximum power. When a loose fit engine is desired the rigid skirt design of the KB piston allows the builder a choice without fear of piston damage. Seethe clearance chart below for minimum and realistic maximum loose fit clearance for KB pistons.

−

*4.165" bore X 0.~~0045" = 0.0166~~, or ~~rounded up~~ to 0.~~017" minimum~~ end gap.

+

;Special Notice on Top Ring End Gap

+

The Keith Black pistons unique thermal conductivity, ring location and varied end use requires special attention be paid to top ring end gap. KB pistons make more HP by reflecting heat energy back into the combustion process and, as a result, the top ring runs hotter and requires additional end clearance. Increasing ring end gap does not affect performance or oil control because normal end gaps are realized at operating temperatures. Failure to provide sufficient top ring end gap will cause a portion of the top ring land to break as the ring ends butt and lock tight in the cylinder. The broken piece may cause further piston or engine damage. Safe top ring end gaps can be found by multiplying the bore diameter by the appropriate ring end gap factor from the clearance chart below.

+

'''Example:''' 4" bore "Street Normally Aspirated" = 4" bore x 0.0065 = 0.026 top ring end gap. NOTE: Second ring end gaps do not need extra clearance. Dyno and track testing has shown that 34 degrees or less total ignition timing makes the best HP and time. Excessive spark advance, lean fuel mixture or too much compression for the fuel and cam used will make heat sufficient to butt piston rings with as much as .060" ring end gap. The entire top land can expand enough to contact the cylinder walls, when close to melt down temperatures are reached.

+

+

<tr>

+

<td bgcolor="#FFF8DC" rowspan="3" class="table_label_two" align="center" valign="top" width="180">'''APPLICATION'''</td>

+

<td bgcolor="#FFF8DC" colspan="3" class="table_label_two" align="center">'''Hypereutectic'''</td>

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<td bgcolor="#FFF8DC" colspan="3" class="table_label_two" align="center">'''Forging'''</td>

+

</tr>

+

<tr>

+

<td bgcolor="#CCCCFF" rowspan="2" class="table_label_two" align="center" width="58">'''Ring End Gap Factor'''</td>

+

<td bgcolor="#CCCCFF" colspan="2" class="table_label_two" align="center">'''Suggested Piston To Wall Clearance'''</td>

+

<td bgcolor="#CCCCFF" rowspan="2" class="table_label_two" align="center" width="70">'''Ring End Gap Factor'''</td>

+

<td bgcolor="#CCCCFF" colspan="2" class="table_label_two" align="center">'''Suggested Piston To Wall Clearance'''</td>

+

</tr>

+

<tr>

+

+

+

+

+

</tr>

+

<tr>

+

<td bgcolor="#FFF8DC" class="row_a" align="left">Street - Normally Aspirated</td>

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+

+

+

+

+

+

</tr>

+

<tr>

+

<td bgcolor="#FFF8DC" class="row_a" align="left">Street - Towing</td>

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+

+

+

+

+

+

</tr>

+

<tr>

+

<td bgcolor="#FFF8DC" class="row_a" align="left">Street - Nitrous or Supercharged</td>

+

+

+

+

+

+

+

</tr>

+

<tr>

+

<td bgcolor="#FFF8DC" class="row_a" align="left">Circle Track - 2 BBL or Restrictor/Gas</td>

+

+

+

+

+

+

+

</tr>

+

<tr>

+

<td bgcolor="#FFF8DC" class="row_a" align="left">Circle Track - Unrestricted</td>

+

+

+

+

+

+

+

</tr>

+

<tr>

+

<td bgcolor="#FFF8DC" class="row_a" align="left">Circle Track - Alcohol Injection</td>

+

+

+

+

+

+

+

</tr>

+

<tr>

+

<td bgcolor="#FFF8DC" class="row_a" align="left">Circle Track - Alcohol Carbureted</td>

+

+

+

+

+

+

+

</tr>

+

<tr>

+

<td bgcolor="#FFF8DC" class="row_a" align="left">Drag - Gasoline</td>

+

+

+

+

+

+

+

</tr>

+

<tr>

+

<td bgcolor="#FFF8DC" class="row_a" align="left">Drag - Alcohol</td>

+

+

+

+

+

+

+

</tr>

+

<tr>

+

<td bgcolor="#FFF8DC" class="row_a" align="left">Drag - Supercharged or Nitrous Gas</td>

+

+

+

+

+

+

+

</tr>

+

<tr>

+

<td bgcolor="#FFF8DC" class="row_a" align="left">Drag - Supercharged Alcohol</td>

+

+

+

+

+

+

+

</tr>

+

<tr>

+

<td bgcolor="#FFF8DC" class="row_a" align="left">Drag - Supercharged Fuel</td>

+

+

+

+

+

+

+

</tr>

+

<tr>

+

<td bgcolor="#FFF8DC" class="row_a" align="left">Marine - Normally Aspirated</td>

+

+

+

+

+

+

+

</tr>

+

<tr>

+

<td bgcolor="#FFF8DC" class="row_a" align="left">Marine - Supercharged</td>

+

+

+

+

+

+

+

</tr>

+

<tr>

+

<td bgcolor="#FFF8DC" class="row_a" align="left">Air Cooled Baja</td>

+

+

+

+

+

+

+

</tr>

+

<tr>

+

<td bgcolor="#FFF8DC"class="row_a" align="left">Propane</td>

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+

+

+

+

+

+

</tr>

+

<tr>

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<td bgcolor="#FFF8DC" class="row_a" align="left">Supercharged Monster Truck / Mudbog</td>

+

+

+

+

+

+

+

</tr>

+

</table>

==SBC oil ring depth==

GM has used both a shallow oil ring and a deep oil ring on SBC engines. Up to 1985 the oil ring/piston groove was 'deep' (0.195" or thereabouts). From about 1986 to the end of the L31 Vortec production, the 'shallow' rings (around 0.165") were used- but there could still be deep groove pistons and rings being used from about '95-back. A page on what to look for is '''[http://www.hastingsmfg.com/ServiceTips/oil_ring_groove_depths.htm Oil Ring Groove Depths]'''.

Pistons and rings

Revision as of 07:49, 11 January 2013

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@@ Line 80: / Line 80: @@
 {{Note1}} See the info at '''SBC oil ring depth''', below.
-==Ring gap examples==
+==KB ring gap and piston to wall clearance instructions==
-===4 inch bore (SBC, SBF, etc.)===
+{{Note1}}The following info is for the KB Icon/Icon FHR (Forged Head Relief) series and some KB hypereutectic pistons. Refer to manufacturer's instructions for other brands and types of pistons.
-*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.)===
+;[http://www.kb-silvolite.com/icon/clearance_pop.php Suggested Piston to Wall Clearance]<nowiki>:</nowiki>
-*4.125" plus 0.040" overbore = 4.165"
+KB pistons can be installed tighter than other performance pistons. A close fitting piston rocks less, supports the rings better and seals the engine for maximum power. When a loose fit engine is desired the rigid skirt design of the KB piston allows the builder a choice without fear of piston damage. Seethe clearance chart below for minimum and realistic maximum loose fit clearance for KB pistons.
-*4.165" bore X 0.0045" = 0.0166, or rounded up to 0.017" minimum end gap.
+;Special Notice on Top Ring End Gap
+The Keith Black pistons unique thermal conductivity, ring location and varied end use requires special attention be paid to top ring end gap. KB pistons make more HP by reflecting heat energy back into the combustion process and, as a result, the top ring runs hotter and requires additional end clearance. Increasing ring end gap does not affect performance or oil control because normal end gaps are realized at operating temperatures. Failure to provide sufficient top ring end gap will cause a portion of the top ring land to break as the ring ends butt and lock tight in the cylinder. The broken piece may cause further piston or engine damage. Safe top ring end gaps can be found by multiplying the bore diameter by the appropriate ring end gap factor from the clearance chart below.
+'''Example:''' 4" bore "Street Normally Aspirated" = 4" bore x 0.0065 = 0.026 top ring end gap. NOTE: Second ring end gaps do not need extra clearance. Dyno and track testing has shown that 34 degrees or less total ignition timing makes the best HP and time. Excessive spark advance, lean fuel mixture or too much compression for the fuel and cam used will make heat sufficient to butt piston rings with as much as .060" ring end gap. The entire top land can expand enough to contact the cylinder walls, when close to melt down temperatures are reached.
+<table border="1" cellpadding="2" cellspacing="0">
+  <tr>
+    <td bgcolor="#FFF8DC" rowspan="3" class="table_label_two" align="center" valign="top" width="180">'''APPLICATION'''</td>
+    <td bgcolor="#FFF8DC" colspan="3" class="table_label_two" align="center">'''Hypereutectic'''</td>
+    <td bgcolor="#FFF8DC" colspan="3" class="table_label_two" align="center">'''Forging'''</td>
+  </tr>
+  <tr>
+    <td bgcolor="#CCCCFF" rowspan="2" class="table_label_two" align="center" width="58"><span class="small_label">'''Ring End Gap Factor'''</span></td>
+    <td bgcolor="#CCCCFF" colspan="2" class="table_label_two" align="center"><span class="small_label">'''Suggested Piston To Wall Clearance'''</span></td>
+    <td bgcolor="#CCCCFF" rowspan="2" class="table_label_two" align="center" width="70"><span class="small_label">'''Ring End Gap Factor'''</span></td>
+    <td bgcolor="#CCCCFF" colspan="2" class="table_label_two" align="center"><span class="small_label">'''Suggested Piston To Wall Clearance'''</span></td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC" class="table_label_two" align="center" width="104">'''Bore to 4.100"</td>
+    <td bgcolor="#FFF8DC" class="table_label_two" align="center" width="106">'''4.100"-up'''</td>
+    <td bgcolor="#FFF8DC" class="table_label_two" align="center" width="92">'''Bore to 4.100"'''</td>
+    <td bgcolor="#FFF8DC" class="table_label_two" align="center" width="106">'''4.100"-up</td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC" class="row_a" align="left"><span class="small_label">Street - Normally Aspirated</span></td>
+    <td class="row_b" align="center">0.0065"</td>
+    <td class="row_a" align="center">0.0015" - 0.0020"</td>
+    <td class="row_b" align="center">0.0020" - 0.0025"</td>
+    <td class="row_a" align="center">0.0040"</td>
+    <td class="row_b" align="center">0.0035" - 0.0045"</td>
+    <td class="row_a" align="center">0.0045" - 0.0055"</td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC" class="row_a" align="left"><span class="small_label">Street - Towing</span></td>
+    <td class="row_b" align="center">0.0080"</td>
+    <td class="row_a" align="center">0.0015" - 0.0020"</td>
+    <td class="row_b" align="center">0.0020" - 0.0025"</td>
+    <td class="row_a" align="center">0.0045"</td>
+    <td class="row_b" align="center">0.0040" - 00.0050"</td>
+    <td class="row_a" align="center">0.0050" - 0.0060"</td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC" class="row_a" align="left"><span class="small_label">Street - Nitrous or Supercharged</span></td>
+    <td class="row_b" align="center">0.0080"</td>
+    <td class="row_a" align="center">0.0020" - 0.0025"</td>
+    <td class="row_b" align="center">0.0025" - 0.0035"</td>
+    <td class="row_a" align="center">0.0050"</td>
+    <td class="row_b" align="center">0.0045" - 0.0055"</td>
+    <td class="row_a" align="center">0.0055" - 0.0065"</td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC" class="row_a" align="left"><span class="small_label">Circle Track - 2 BBL or Restrictor/Gas</span></td>
+    <td class="row_b" align="center">0.0070"</td>
+    <td class="row_a" align="center">0.0015" - 0.0045"</td>
+    <td class="row_b" align="center">0.0020" - 0.0050"</td>
+    <td class="row_a" align="center">0.0040"</td>
+    <td class="row_b" align="center">0.0040" - 0.0050"</td>
+    <td class="row_a" align="center">0.0055" - 0.0065"</td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC" class="row_a" align="left"><span class="small_label">Circle Track - Unrestricted</span></td>
+    <td class="row_b" align="center">0.0080"</td>
+    <td class="row_a" align="center">0.0025" - 0.0045"</td>
+    <td class="row_b" align="center">0.0030" - 0.0045"</td>
+    <td class="row_a" align="center">0.0040"</td>
+    <td class="row_b" align="center">0.0045" - 0.0065"</td>
+    <td class="row_a" align="center">0.0055" - 0.0075"</td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC" class="row_a" align="left"><span class="small_label">Circle Track - Alcohol Injection</span></td>
+    <td class="row_b" align="center">0.0060"</td>
+    <td class="row_a" align="center">0.0025" - 0.0045"</td>
+    <td class="row_b" align="center">0.0025" - 0.0050"</td>
+    <td class="row_a" align="center">0.0040"</td>
+    <td class="row_b" align="center">0.0045" - 0.0065"</td>
+    <td class="row_a" align="center">0.0055" - 0.0075"</td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC" class="row_a" align="left"><span class="small_label">Circle Track - Alcohol Carbureted</span></td>
+    <td class="row_b" align="center">0.0080"</td>
+    <td class="row_a" align="center">0.0030" - 0.0045"</td>
+    <td class="row_b" align="center">0.0030" - 0.0050"</td>
+    <td class="row_a" align="center">0.0045"</td>
+    <td class="row_b" align="center">0.0050" - 0.0070"</td>
+    <td class="row_a" align="center">0.0060" - 0.0080"</td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC" class="row_a" align="left"><span class="small_label">Drag - Gasoline</span></td>
+    <td class="row_b" align="center">0.0075"</td>
+    <td class="row_a" align="center">0.0015" - 0.0045"</td>
+    <td class="row_b" align="center">0.0020" - 0.0045"</td>
+    <td class="row_a" align="center">0.0040"</td>
+    <td class="row_b" align="center">0.0050" - 0.0070"</td>
+    <td class="row_a" align="center">0.0060" - 0.0080"</td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC" class="row_a" align="left"><span class="small_label">Drag - Alcohol</span></td>
+    <td class="row_b" align="center">0.0065"</td>
+    <td class="row_a" align="center">0.0015" - 0.0045"</td>
+    <td class="row_b" align="center">0.0020" - 0.0045"</td>
+    <td class="row_a" align="center">0.0040"</td>
+    <td class="row_b" align="center">0.0040" - 0.0070"</td>
+    <td class="row_a" align="center">0.0050" - 0.0080"</td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC" class="row_a" align="left"><span class="small_label">Drag - Supercharged or Nitrous Gas</span></td>
+    <td class="row_b" align="center">0.0095"</td>
+    <td class="row_a" align="center">0.0020" - 0.0045"</td>
+    <td class="row_b" align="center">0.0025" - 0.0050"</td>
+    <td class="row_a" align="center">0.0050"</td>
+    <td class="row_b" align="center">0.0060" - 0.0090"</td>
+    <td class="row_a" align="center">0.0070" - 0.0100"</td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC" class="row_a" align="left"><span class="small_label">Drag - Supercharged Alcohol</span></td>
+    <td class="row_b" align="center">0.0085"</td>
+    <td class="row_a" align="center">0.0015" - 0.0045"</td>
+    <td class="row_b" align="center">0.0025" - 0.0045"</td>
+    <td class="row_a" align="center">0.0050"</td>
+    <td class="row_b" align="center">0.0050" - 0.0070"</td>
+    <td class="row_a" align="center">0.0060" - 0.0080"</td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC" class="row_a" align="left"><span class="small_label">Drag - Supercharged Fuel</span></td>
+    <td class="row_b" align="center">0.0115"</td>
+    <td class="row_a" align="center">0.0030" - 0.0050"</td>
+    <td class="row_b" align="center">0.0035" - 0.0055"</td>
+    <td class="row_a" align="center">0.0060"</td>
+    <td class="row_b" align="center">0.0070" - 0.0100"</td>
+    <td class="row_a" align="center">0.0080" - 0.0110"</td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC" class="row_a" align="left"><span class="small_label">Marine - Normally Aspirated</span></td>
+    <td class="row_b" align="center">0.0080"</td>
+    <td class="row_a" align="center">0.0030" - 0.0045"</td>
+    <td class="row_b" align="center">0.0035" - 0.0050"</td>
+    <td class="row_a" align="center">0.0040"</td>
+    <td class="row_b" align="center">0.0045" - 0.0060"</td>
+    <td class="row_a" align="center">0.0055" - 0.0070"</td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC" class="row_a" align="left"><span class="small_label">Marine - Supercharged</span></td>
+    <td class="row_b" align="center">0.0090"</td>
+    <td class="row_a" align="center">0.0030" - 0.0045"</td>
+    <td class="row_b" align="center">0.0035" - 0.0050"</td>
+    <td class="row_a" align="center">0.0045"</td>
+    <td class="row_b" align="center">0.0055" - 0.0070"</td>
+    <td class="row_a" align="center">0.0065" - 0.0080"</td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC" class="row_a" align="left"><span class="small_label">Air Cooled Baja</span></td>
+    <td class="row_b" align="center">0.0075"</td>
+    <td class="row_a" align="center">0.0030" - 0.0045"</td>
+    <td class="row_b" align="center">0.0035" - 0.0050"</td>
+    <td class="row_a" align="center">0.0040"</td>
+    <td class="row_b" align="center">0.0050" - 0.0070"</td>
+    <td class="row_a" align="center">0.0060" - 0.0080"</td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC"class="row_a" align="left"><span class="small_label">Propane</span></td>
+    <td class="row_b" align="center">0.0065"</td>
+    <td class="row_a" align="center">0.0015" - 0.0045"</td>
+    <td class="row_b" align="center">0.0020" - 0.0045"</td>
+    <td class="row_a" align="center">0.0040"</td>
+    <td class="row_b" align="center">0.0035" - 0.0070"</td>
+    <td class="row_a" align="center">0.0045" - 0.0080"</td>
+  </tr>
+  <tr>
+    <td bgcolor="#FFF8DC" class="row_a" align="left"><span class="small_label">Supercharged Monster Truck / Mudbog</span></td>
+    <td class="row_b" align="center">0.0090"</td>
+    <td class="row_a" align="center">0.0025" - 0.0045"</td>
+    <td class="row_b" align="center">0.0030" - 0.0050"</td>
+    <td class="row_a" align="center">0.0060"</td>
+    <td class="row_b" align="center">0.0080" - 0.0100"</td>
+    <td class="row_a" align="center">0.0090" - 0.0110"</td>
+  </tr>
+</table><br>
 ==SBC oil ring depth==
 GM has used both a shallow oil ring and a deep oil ring on SBC engines. Up to 1985 the oil ring/piston groove was 'deep' (0.195" or thereabouts). From about 1986 to the end of the L31 Vortec production, the 'shallow' rings (around 0.165") were used- but there could still be deep groove pistons and rings being used from about '95-back. A page on what to look for is '''[http://www.hastingsmfg.com/ServiceTips/oil_ring_groove_depths.htm Oil Ring Groove Depths]'''.