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| − | {{develop1}}
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| − | ==Overview==
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| − | Swirl port SBC heads are often overlooked for any kind of performance use. This page will weigh the pros and cons of using them in a "street performance" application.
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| − | ==History==
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| − | The SBC swirl port heads came to be in about 1987.
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| − | ==Casting numbers and ID==
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| − | The 1987-up 5.7L TBI truck engines (also some marine engines) used c/n 14102191. Casting number 14102193 heads were also used on 1987-up truck engines and is also used on the 305 RPO LO3 engine.
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| − | Both heads use center bolt valve covers.
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| − | *191 have 76cc combustion chambers
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| − | *193 have 64cc combustion chambers
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| − | ==Design limitations==
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| − | Its not that Swirlies outflow Vortec, its that they burn better and require less timing, generating more net torque. Less total timing = less negative work on the crankshaft as cylinder pressure is building. Up to 4,500 rpm many other heads cannot touch them. Where Vortecs like up to 12-16* of advance right off idle and as much as 32-34* total at high rpm, the Swirlies run best with only 4-6* of timing off-idle and 26-30* at high rpm.
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| − | ===TBI swirl-inducing vane===
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| − | [[File:Tbi swirl port vane1.jpg|thumb|left|350px|TBI swirl port vane (arrow)]][[File:Used 193-1.jpg|thumb|left|550px|TBI swirl port vane, paired combustion chambers]]
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| − | <br style="clear:both"/>
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| − | ===L30 5.0L Vortec head===
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| − | Some info and photos of the L30 5L Vortec head at [http://www.nastyz28.com/forum/showthread.php?t=56505&page=32 post 478].
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| − | {|
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| − | |[[file:305_VORTEC_SWIRL_RAMP_CN_059.jpg|thumb|220px|center|305 Vortec L30 casting number 12558059]]
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| − | |[[File:305 VORTEC CHAMBER CN 059.jpg|thumb|500px|center|305 Vortec L30 casting number 12558059 chamber]]
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| − | |[[File:L31 305 VORTEC HEAD CASTING ID.jpg|500px|thumb|center|305 Vortec L30 casting ID]]
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| − | |}
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| − | ==Modifications and porting==
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| − | *[http://www.youtube.com/watch?v=QMkCV1s5BQ8 Video] showing port work on a c/n 193 swirl port head.
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| − | ==Resources==
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| − | *[http://www.mortec.com/castnum.htm SBC Heads casting numbers] by Mortec
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| − | *[http://outintheshop.com/faq/casting/castings2.html SBC head casting number go-to site]
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| − | [[Category:Engine]]
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| − | [[Category:GM]]
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| − | [[Category:Cylinder head]]
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