Vortec L31 cylinder head
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;'''Sources:''' | ;'''Sources:''' | ||
| − | :Paul Shufelt | + | :Paul Shufelt, Chevy High Performance (Feb. 2001) |
| − | + | ||
==Upgrading and Compatibility== | ==Upgrading and Compatibility== | ||
The L31 Vortec head will bolt directly onto Gen 1 small block Chevrolets. They will also obviously work on L31 engines (sometimes referred to as Gen1+). They are not compatible with Gen2 (LT1 or LT4) engines. They are also not compatible with any of the current LS engines. | The L31 Vortec head will bolt directly onto Gen 1 small block Chevrolets. They will also obviously work on L31 engines (sometimes referred to as Gen1+). They are not compatible with Gen2 (LT1 or LT4) engines. They are also not compatible with any of the current LS engines. | ||
| − | There are however, some inherent costs associated in swapping 1995-back heads | + | There are however, some inherent costs associated in swapping from 1995-back heads to the L31 Vortec heads. Here is a list of items to be purchased and/or labor associated with the upgrade: |
* L31 heads (and required hardware like springs, valves, retainers, valve keepers, etc) | * L31 heads (and required hardware like springs, valves, retainers, valve keepers, etc) | ||
* Center bolt style valve covers if the heads used previously were perimeter style | * Center bolt style valve covers if the heads used previously were perimeter style | ||
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* Head bolts (required only if the original head bolts are either missing or unusable for some reason) | * Head bolts (required only if the original head bolts are either missing or unusable for some reason) | ||
* Head gaskets ([http://www.crankshaftcoalition.com/wiki/Head_gasket#Re-using_head_gaskets generally required] any time heads are re-installed) | * Head gaskets ([http://www.crankshaftcoalition.com/wiki/Head_gasket#Re-using_head_gaskets generally required] any time heads are re-installed) | ||
| − | * Grinding down valve guides or the use of different retainers and springs, or ghetto grinding the stock retainers, etc., to work with a camshaft having somewhere around 0.480" or more valve lift. | + | * Grinding down valve guides or the use of different retainers and springs, or ghetto grinding the stock retainers, etc., to work with a camshaft having somewhere around 0.480" or more valve lift. |
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| + | {{Note1}} The clearance between the retainer and the seal has to be checked during the engine mock up phase of the build to determine exactly what the clearance is with the cam, retainer, valve stem seal, valve locks and rocker arm/rocker arm ratio used. | ||
==Valves== | ==Valves== | ||
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So both the c/n 906 and c/n 062 heads have virtually the same performance potential. In fact c/n 906 heads having the hardened inserts are actually preferred by some performance engine builders, mainly for marine applications. Later production c/n 906 heads stopped using exhaust seat inserts and at some point, all Vortec head exhaust seats were induction hardened. | So both the c/n 906 and c/n 062 heads have virtually the same performance potential. In fact c/n 906 heads having the hardened inserts are actually preferred by some performance engine builders, mainly for marine applications. Later production c/n 906 heads stopped using exhaust seat inserts and at some point, all Vortec head exhaust seats were induction hardened. | ||
| − | + | '''From GMPP:''' | |
| − | From GMPP: | + | |
:The #906 casting head was available in two versions. One has an Inconel exhaust seat with a single angle grind, and the other has the conventional 3-angle grind on the exhausts as per the #062. The #906 with Inconel seat does not intrude into the exhaust port. It was used primarily on the HD and 1-ton truck applications where sustained towing of heavy loads & weight up inclines could cause eventual damage to a standard induction-hardened exhaust seat from excessive heat. | :The #906 casting head was available in two versions. One has an Inconel exhaust seat with a single angle grind, and the other has the conventional 3-angle grind on the exhausts as per the #062. The #906 with Inconel seat does not intrude into the exhaust port. It was used primarily on the HD and 1-ton truck applications where sustained towing of heavy loads & weight up inclines could cause eventual damage to a standard induction-hardened exhaust seat from excessive heat. | ||
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[[File:Vortec head p-rod hole enlargement.jpg|thumb|Vortec head enlarging pushrod hole]]Vortec heads have a 7/16" round pushrod hole in the head; earlier non self aligning rocker arm equipped heads have a 7/16" x 11/32" ovoid hole in them. | [[File:Vortec head p-rod hole enlargement.jpg|thumb|Vortec head enlarging pushrod hole]]Vortec heads have a 7/16" round pushrod hole in the head; earlier non self aligning rocker arm equipped heads have a 7/16" x 11/32" ovoid hole in them. | ||
| − | So what this means is three things: | + | ===So what this means is three things:=== |
* Without resorting to welding up the holes to form slots to provide side to side alignment, Vortec heads cannot be used w/non self aligning rockers unless guide plates are used. Heads can use guide slots, OR guide plates, OR self aligning rockers, but only ONE of the three at any given time. | * Without resorting to welding up the holes to form slots to provide side to side alignment, Vortec heads cannot be used w/non self aligning rockers unless guide plates are used. Heads can use guide slots, OR guide plates, OR self aligning rockers, but only ONE of the three at any given time. | ||
* If using 1.6 ratio rockers, there's a chance the Vortec's 7/16" hole will not be large enough. A Lewis tool will not work, so instead, a drill bit larger than 7/16" can be used to open the pushrod holes up. Most often a 1/2” bit is used, but in any event use what ever size is needed to get the needed clearance. The push rod hole can also be lengthened with a grinding tool like a Dremel or die grinder. As a last resort this can be done using files. | * If using 1.6 ratio rockers, there's a chance the Vortec's 7/16" hole will not be large enough. A Lewis tool will not work, so instead, a drill bit larger than 7/16" can be used to open the pushrod holes up. Most often a 1/2” bit is used, but in any event use what ever size is needed to get the needed clearance. The push rod hole can also be lengthened with a grinding tool like a Dremel or die grinder. As a last resort this can be done using files. | ||
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[[Category:Engine]] | [[Category:Engine]] | ||
[[Category:GM]] | [[Category:GM]] | ||
| + | [[Category:Cylinder head]] | ||
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