Cadillac Big Block 425-500 Straight Lake Header Kit


Includes One Straight Lake Header Kit for the Big Block Cadillac 425, 472, 500 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.


Kit includes: 

1 pair – 30″ long steel megaphones (1-5/8″ inlet & 3-1/2″ outlet) – 4″ outlet available upon request

2 – 2″ OD, 0.065″ wall plain steel (not aluminized!) 70 degree mandrel bends

6 – 2″ OD, 0.065, 10″ long plain steel tubing

1 pair – 3/8″ thick exhaust flanges – specific motor application listed above

(photo is shown just for reference, contents listed above is actually what you will receive)


Motor Application:

Big Block Cadillac

            425 cu. in (1977-79)

            472 cu in (1968-74)

            500 cu in (1970-76)

            *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.

1 review for Cadillac Big Block 425-500 Straight Lake Header Kit

  1. William Weise (verified owner)

    Just opened the box, am very impressed with the quality of the parts. Was surprised to see the thickness of the header flanges. Everything looks like it will work perfectly.

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