GT-500 intake questions

[Mike_Senar]

Hello,
 Pictured is (what I have thought) is an original manifold.  Plenums are original and not cut.  Casted this way!  Why are most I see not like this one?
              Mike

[Bob Gaines]

Hello,
 Pictured is (what I have thought) is an original manifold.  Plenums are original and not cut.  Casted this way!  Why are most I see not like this one?
              Mike

Plenums appear to be after the fact go fast modified. The casting process would initially have the 4 holes in each . Regardless of if you can make a case that the plenums were modified by a previous owner or not, extra "machining" is necessary to make the cuts. They are not as cast like you state. My opinion is it was done after the fact for go fast reasons.

[Coralsnake]

Agreed , it looks modified

[Mike_Senar]

Hello,
 Here are a couple more pictures now thst I have made it back to the manifold.  I do not see any cutting or grinding marks anywhere on these plenums...

[pbf777]

    Yes, definitely "modified"; that from as it was produced by the O.E.M.. 

    This was/is a popular modification, which is most efficiently accomplished with a "plunge-cut" from an end-mill and then "deburred" to remove the sharp edges, this to increase the effective area of the "plenum" and thereby in an attempt to extend upward the R.P.M. functional range than would be otherwise. 

    Scott.

[Road Reptile]

Hi Mike,
Looks like a good manifold if this is the only thing modified. Would be very wise to clean up and sell if you don't need it.
R.R.

[FL SAAC]

Once carbs are on no one will notice.

"Its all stock"

Should have a much better top end, enjoy.

Merry Christmas

[Mike_Senar]

Hello RR,
  That is mostly the plan as I now have a "Shelby" version of this (mid-rise) manifold, and I do not own a '67 GT-500 car.
                                                             Mike