Editing Swirl port SBC heads

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==Overview==
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.

==History==
The SBC swirl port heads came to be in about 1987.

==Casting numbers and ID==
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.

Both heads use center bolt valve covers.

*191 have 76cc combustion chambers
*193 have 64cc combustion chambers

==Design limitations==
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.

===TBI swirl-inducing vane===
[[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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===L30 5.0L Vortec head=== 
Some info and photos of the L30 5L Vortec head at [http://www.nastyz28.com/forum/showthread.php?t=56505&page=32 post 478].
{|
|[[file:305_VORTEC_SWIRL_RAMP_CN_059.jpg|thumb|220px|center|305 Vortec L30 casting number 12558059]]
|[[File:305 VORTEC CHAMBER CN 059.jpg|thumb|500px|center|305 Vortec L30 casting number 12558059 chamber]]
|[[File:L31 305 VORTEC HEAD CASTING ID.jpg|500px|thumb|center|305 Vortec L30 casting ID]]
|}

==Modifications and porting==
*[http://www.youtube.com/watch?v=QMkCV1s5BQ8 Video] showing port work on a c/n 193 swirl port head.

==Resources==
*[http://www.mortec.com/castnum.htm SBC Heads casting numbers] by Mortec
*[http://outintheshop.com/faq/casting/castings2.html SBC head casting number go-to site]


[[Category:Engine]]
[[Category:GM]]
[[Category:Cylinder head]]