Porting 430 heads and intake manifold

Discussion in 'Street/strip 400/430/455' started by Sebastian, Jan 9, 2020.

  1. Sebastian

    Sebastian Active Member


    had my heads out for porting. Yeah I know its not for beginners but otherwise I dont will get any knowledge for the engine.

    So first is there any value to port the intake manifold also? For sure I will smooth the inner and remove the casting marks and match the gasket. Is there any more recommend positions?

    Does somebody have some before and after pictures of ported 430/455 iron heads?
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Be careful if you port the manifold. You don't want a situation where the manifold ports are bigger than the head ports. You are way better off with them being smaller.
    john.schaefer77 likes this.
  3. tommieboy

    tommieboy Well-Known Member

    On my old "Banker's Hotrod" Buick 455 engines with mildly ported heads and camshafts, I was told to leave the cast iron intake alone as there was nothing to be gained there at my power levels. But that was 30+ years ago, and I always ran the stock cast iron exhausts too.

  4. hugger

    hugger Well-Known Member

    Dont smooth the intake runners you want them rough finish to promote fuel tumble,..dont really enlarge the runners just "square" them up and it will be fine
  5. Stevem

    Stevem Well-Known Member

    Times 2 with the above!
    On the Intake side of the flow system be it head or Intake Manifold you don't want smooth, you want a as cast finish with just no small pimple like obstructions.
    The only part of a total Intake system that can be Baby's Ass smooth is around the heads short turn be it Intake or Exh, otherwise on the Intake side of things for example you do not want the finish any smoother then what 180 grit sand paper feels like.
  6. Billy

    Billy Well-Known Member

    On the intake manifold,
    The roof is the only part to port and smooth, then put a glass bead finish on it.
    Leave the floor and sides alone.
    Also just clean up the runners, leave them stock size as possible and make sure they are smaller then the runners on the heads you will be using.
  7. Stevem

    Stevem Well-Known Member

    Let me detail what was posted above if I might?
    Smaller at the junction of the head and Manifold flange only, such that minor misalignment of the Manifold will not make the air coming down the Intake runners slam into a lip on the head flange.
    The ideal Intake runner would expand in area from that junction point on back towards the Plenum, necking down the other way will only serve to narrow up on the motors power band and make both the HP and Torque number nose over faster once each has respectively hit there peak.
  8. Billy

    Billy Well-Known Member

    When the feather is fluttering under flow.
    There is an obstruction?

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