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Ported Ls3 823 heads from Noland's cylinder heads in KCMO. Milled .020. valve job. Qualcast black lightning valves. PAC KS-11 springs rated at .625 lift. Car ls3 manifold.

These have zero miles since porting. Bought for my GTO and never installed.
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Chickun maka lousy houspet
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I know stock 823's flow around 55 CFM more over stock 243's on the intake side and around 30 CFM on the exhaust side.

I looked up the STOCK valves sizes:
243's
  • INT: 2.000"
  • EXH: 1.550"

823's
  • INT: 2.165" (roughly 8.2% larger)
  • EXH: 1.590" (roughly 2.6% larger)
 
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