Vortec L31 cylinder head
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'''[[Vortec_L31_cylinder_head#Upgrading and Compatibility|Return to above]]''' | '''[[Vortec_L31_cylinder_head#Upgrading and Compatibility|Return to above]]''' | ||
| − | ==Vortec | + | ==Vortec intake manifolds== |
| − | 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 | + | 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, so using a carb or TBI with Vortec heads is easy. Some GMPP Vortec intakes have the provision to run coolant through the plenum area to provide intake heat. |
| − | Vortec heads use an intake manifold having 8 instead of 12 bolts. Also, Vortec intake ports are taller than earlier SBC heads | + | ===Using an early style intake on an aftermarket Vortec-type head=== |
| + | Vortec heads use an intake manifold having 8 instead of 12 bolts. Also, Vortec intake ports are taller than earlier SBC heads; there's not enough metal above the port (except on "raised port" aftermarket intakes) to allow the head and intake port to match up. That means earlier 12 bolt intakes will not match up to the Vortec bolt pattern or ports. | ||
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| + | Many aftermarket Vortec style heads (including Bow Tie Vortec heads) feature dual bolt patterns allowing the use of the early 12-bolt intakes. This has a very limited use. | ||
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| + | Commonly available 12 bolt SBC dual plane intakes do not have enough metal above the port to be ported to match the Vortec port, w/o having a vacuum leak or razor thin sealing surfaces above the ports. An early intake would need at least 0.325" of material above the intake port opening to have any chance of sealing, and that doesn't take the difference in the port width/location into account. Because of the height of the Vortec intake port, only the single plane 'raised port' race intakes have enough height to actually mate to the Vortec port- but even then the ports may be too wide or have other port fitment issues. | ||
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| + | Because of these differences, a Vortec-specific intake should be used. | ||
;Chevrolet says<nowiki>:</nowiki> | ;Chevrolet says<nowiki>:</nowiki> | ||
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</blockquote> | </blockquote> | ||
| − | Due to issues with | + | Due to issues with some Vortec intake manifold gaskets (vacuum and coolant leaks), it is suggested to use a Fel-Pro gasket p/n Q1255 intake gasket, or equivalent. |
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