Vortec L31 cylinder head
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:Paul Shufelt | :Paul Shufelt | ||
:Chevy High Performance (Feb. 2001) | :Chevy High Performance (Feb. 2001) | ||
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| + | ==Upgrading and Compatibility== | ||
| + | The L31 Vortec head will bolt directly onto Gen 1 small block Chevrolet's. 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. | ||
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| + | There are however, some inherent costs associated in swapping your old bath tub heads with L31's. 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) | ||
| + | * Center bolt style valve covers | ||
| + | ** Note: part# 25534351 or 25534421 will accept either perimeter or center bolt valve covers, but heads removed from a production donor vehicle will require center bolt valve covers [http://www.crankshaftcoalition.com/wiki/Vortec_L31_cylinder_head#Small_port_Vortec_head_p.2Fn_25534351_.28bare.29_and_p.2Fn_25534421_.28assembled.29] | ||
| + | * Valve cover gaskets | ||
| + | * Vortec specific intake manifold | ||
| + | * Vortec specific intake manifold gasket | ||
| + | * Vortec specific intake manifold bolts | ||
| + | * Head bolts (required any time heads are re-installed regardless) | ||
| + | * Head gasket (generally required any time heads are re-installed [http://www.crankshaftcoalition.com/wiki/Head_gasket#Re-using_head_gaskets]) | ||
| + | * Grinding down valve guides to accept higher lift (required only if using a cam ~.480"+ lift) | ||
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==Valves== | ==Valves== | ||
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The stock springs are not suited for high performance use. There are several replacements for the stock springs, among the best is the beehive spring and retainer combination from Comp Cams, originally designed for the LSx engine series. There are two part numbers for the different spring rates: | The stock springs are not suited for high performance use. There are several replacements for the stock springs, among the best is the beehive spring and retainer combination from Comp Cams, originally designed for the LSx engine series. There are two part numbers for the different spring rates: | ||
| − | + | •'''[http://www.compcams.com/WhatsNew/NewsDetails.aspx?ListHistoryID=164462240 26915]'''- 105 pounds at 1.8" installed height; 293 pounds at 1.2" (according to Competition Products catalog info); spring rate 313 lbs./in (according to Summit Racing catalog info) | |
| − | + | •'''[http://www.compcams.com/WhatsNew/NewsDetails.aspx?ListHistoryID=1166393320 26918]'''- 125 pounds at 1.8" installed height; 367 pounds at 1.15" | |
==Valve spring retainers== | ==Valve spring retainers== | ||
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==Vortec specific intake manifolds== | ==Vortec specific intake manifolds== | ||
| − | Vortec heads use an intake manifold having 8 instead of 12 bolts. Also, Vortec intake ports are taller and narrower than earlier SBC heads. That means earlier intakes will not match up to the Vortec ports; there's not enough metal above the port (except on "raised port" aftermarket intakes) to allow the head and intake port to match up. Because of these differences, a Vortec-only intake must be used. | + | Vortec heads use an intake manifold having 8 instead of 12 bolts. Also, Vortec intake ports are taller and narrower than earlier SBC heads. That means earlier intakes will not match up to the Vortec ports; there's not enough metal above the port (except on "raised port" aftermarket intakes) to allow the head and intake port to match up. Because of these differences, a Vortec-only intake must be used. Due to issues with aftermarket Vortec intake manifold gaskets deteriorating for no apparent reason, it is suggested to either use a genuine GM gasket or a Fel-Pro gasket (part# Q1255). |
The L30 5.0L and L31 5.7L Vortec engines never came with a carb; they all used EFI so did not need a heat crossover port in the heads. GMPP and the aftermarket sell various carburetor and TBI intakes to fit the Vortec heads, though, so using a carb or TBI with Vortec heads is easy and some Vortec intakes have the provision to run coolant through the plenum area to provide intake heat. | The L30 5.0L and L31 5.7L Vortec engines never came with a carb; they all used EFI so did not need a heat crossover port in the heads. GMPP and the aftermarket sell various carburetor and TBI intakes to fit the Vortec heads, though, so using a carb or TBI with Vortec heads is easy and some Vortec intakes have the provision to run coolant through the plenum area to provide intake heat. | ||
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==Recommended spark plugs== | ==Recommended spark plugs== | ||
The exact heat range depends on several factors. This is a guide that will get you in the ballpark. Carefully assess the heat range before settling on a plug for your particular combination. | The exact heat range depends on several factors. This is a guide that will get you in the ballpark. Carefully assess the heat range before settling on a plug for your particular combination. | ||
| − | + | * AC Delco Rapid Fire Spark Plugs R44LTS | |
| − | + | * AC Delco Rapid Fire Spark Plugs MR43LTS | |
| − | + | * AC Delco Rapidfire No 3 Spark Plug | |
| − | + | * ACCEL P526S U-Groove “SHORTY” Double Platinum (approximately 3/16″ shorter than AC R44LTS) | |
| − | + | * ACCEL 516 | |
| − | + | * Autolite 26 | |
| − | + | * Autolite 104 | |
| − | + | * Champion RS12YC | |
| − | + | * Bosch HR10B | |
| − | + | * Bosch HR10BX | |
| − | + | * Bosch HR9DC | |
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==Links== | ==Links== | ||
| − | *Nasty Z28.com forum thread, [http://www.nastyz28.com/forum/showthread.php?t=56505 Vortec Cylinder Heads: The Definitive Guide] | + | * Nasty Z28.com forum thread, [http://www.nastyz28.com/forum/showthread.php?t=56505 Vortec Cylinder Heads: The Definitive Guide] |
| − | *[http://www.chevyhiperformance.com/howto/97458/index.html Iron Vortec Head All the Details You Need to Know] from the February, 2009 issue of ''Chevy High Performance''. | + | * [http://www.chevyhiperformance.com/howto/97458/index.html Iron Vortec Head All the Details You Need to Know] from the February, 2009 issue of ''Chevy High Performance''. |
==Resources== | ==Resources== | ||
| − | *[[Valve train points to check]] | + | * [[Valve train points to check]] |
[[Category:Engine]] | [[Category:Engine]] | ||
[[Category:GM]] | [[Category:GM]] | ||
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