Oldsmobile Big Block 350-455 Exhaust Flange


Includes one pair of exhaust flanges for the Big  Block Oldsmobile 400, 425, 455 hot rod motor (see motor applications below).  These flanges are cut with a CNC HD (High Definition) Plasma cutter out of 3/8” Pickled and Oiled (P&O) steel.  P&O material is hot rolled steel that has been dipped in acid to remove the mill scale and then lightly coated with oil.  The end result is less work to clean off the mill scale as needed with hot rolled mild steel.


Motor Application:

Big Block Oldsmobile

            400 cu. in (1965-74)

            425 cu in (1965-74)

            455 cu in (1965-74)

            *more applications/years may work, verify before purchasing.


Ports designed to be used with 2” exhaust tubing.


These flanges are designed in CAD and are test fit on an actual head to make sure proper fitment is achieved.

3 reviews for Oldsmobile Big Block 350-455 Exhaust Flange

  1. Frank Davenport (verified owner)

    Second time I’ve bought exhaust flanges from here. Great products and will use for future builds.

  2. Anonymous

    worked good,not the prettiest welds but i’ll credit that to my crappy century welder, and my incompetence.

  3. Anonymous

    The flanges fit perfectly, clean and flat.I only wish I new the rectangle stub tubes needed to be welded in at the factory, well I will have that done real soon

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