GM did not produce a two barrel manifold for the automotive 250 in the United States.

Brazil 2 Barrel Manifold, Solex H34, Alcohol
http://produto.mercadolivre.com.br/MLB-2...a-weber-446-_JM
http://produto.mercadolivre.com.br/MLB-2...o-solex-h34-_JM

Brazil 2 Barrel Manifold, Weber DFV446, Gasoline
http://produto.mercadolivre.com.br/MLB-212891415-coletor-admisso-opala-caravam-6-cc-_JM
http://produto.mercadolivre.com.br/MLB-216806636-coletor-admisso-3e-446-weber-usado-opala-_JM

Argentina 2 Barrel Manifold
http://articulo.mercadolibre.com.ar/MLA-...chevy-coupe-_JM

As the six cylinder engine is tilled down in the rear when mounted in the car/truck, the front/mid/rear intake ports are at different elevations. The different manifolds deal with this differently.

1)The GM USA OEM stock manifold, 2)the Offenhauser manifold, and 3 & 4)the two Brazilian manifolds have level main runners (manifold runners that are parallel with the engine centerline), and slope the front/mid/rear port runners at different angles. While the OEM and the Offenhauser manifold have the main runners at the mid port level, the Brazilian manifold main runners are slightly higher at the front port level.

The GM USA OEM stock manifold has the plenum bottom at a low point, assuming to prevent liquid gasoline from just running to a particular cylinder.
The approach angle of the rear port runner to the cylinder head is fairly steep on the Brazilian manifolds.

The 5) Argentine and 6) Clifford manifolds have main runners that slope with the engine. The carburetor base is level though. I would be concerned with liquid gasoline overwhelming the rear cylinders. As you can see from the links, the runner volume for the Argentine manifold is less than for the Clifford manifold.

A Brazilian two piece cast iron manifold (1 3/4" I.D.), from a 1995-98 fuel injection 250 engine (looks better right-side-up)
http://produto.mercadolivre.com.br/MLB-221975263-coletor-de-escape-omega-41-9498-_JM
The runners on the carburetor intake manifolds must be lengthen to fit with the Brazilian two piece cast iron manifold.





Last edited by Winter; 02/24/12 08:43 PM.