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    • #57042

      I noticed that the intake ports on the stock manifold are much smaller than those on the head. Even on a later aluminium (4 barrel) manifold that I have ready to fit, the ports are just as small.

      I reckon that its worth matching up the manifold and intake port sizes to get rid of the sudden change in cross section. I would think this should improve gas flow.

      Any thoughts comments?

    • #61654

      Port matching is a very common performance modification. Make sure that the manifold ports do not get larger than the head ports. A step from smaller to lager is preferable than a larger to small step that will cause a hard shelf air turbulence problem. Of course, a perfect port match is the best. Don’t forget to port match the gaskets too.

      I do not recommend any polishing of the intake tract. You want some surface tension to help mix the air/fuel.

    • #61656

        Its ok to polish intake runners, just dont polish them to a high shine, leave a textured swirled surface on the runner and it will help the fuel swirl. here is an image of the finish on my intakes on my alpine, little hard to see but yuo get the idea: … 2410eVpdnv

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