Editing Swirl port SBC heads

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==History==
 
==History==
The SBC swirl port heads came to be in about 1987.
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The SBC swirl port heads came to be in about 1987. They were used with TBI (throttle body injection) EFI (electronic fuel injection) applications in trucks. Their reason to be was for making good low rpm torque while getting acceptable mileage. This design was first used during the mid-1980s on the GM 2.0L inline four used in the Cavalier - usage of the swirl port was later used on the 4.3L V6 motor in 1985.
  
 
==Casting numbers and ID==
 
==Casting numbers and ID==
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==Design limitations==
 
==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===
 
===TBI swirl-inducing vane===
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