Tech:Engine/K Series/Intake manifolds
Intake manifolds for 3k / 4k
From what I know there are basically 4 different OME inlet manifolds for a 3/4 k that support single carby. Bigport (30mm) with bent runners. (Runners shrink in size in between head and plenum) Bigport (30mm) with straight runners. (Runners stay consistent in size and feed 2 to 1 then 2 to plenum) Mid port (27mm) with bent runners. (Runners stay consistent in size and feed 4 to 1) Small port (25mm) with bents runners. (stock) The bigport with straight runner has other issues, It's plenum area is small you could hog this out, and it does not support a dual exhaust manifold so any HP gains in the inlet will be lost in the exhaust, you could get around the exhaust issue with extractors.
Here's some pix to tell the story.
Common small port as we all know and love.
Midport I suspect these are on 4k and later but now sure.
Early biport I think.
Bigport straight plenum area.
Bigport straight runner sizes.
Bigport straight note exhaust triangle is 180 deg out.
Bigport straight exhaust manafold.
Article by Andy43 / Towe001
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