Donald Farr
Former Editor, Mustang Monthly
July 1, 2009

If a Mustang has scoops, then they should scoop something. That was Brit White's thinking when he added functional ram-air to his '73 Mach 1 during its renovation at Restomods Plus in Clearwater, Florida. His 351 Cleveland-powered fastback had the NACA-scooped hood and remnants of former functionality, but most of the major pieces were missing. Thanks to National Parts Depot, Restomod Plus owner Wayne Farnham was able to round up the rest of the pieces needed to ram outside air into the Mach 1's air cleaner

Unlike the previous '69-'70 Mustangs that utilized a through-the-hood Shaker scoop for functional ram-air, the '71-'73 models with optional Ram-Air used a pair of NACA-style (Ford also called them NASA-style) hoodscoops with a large underhood plenum to funnel air into the air cleaner, which incorporated a smaller diameter lid to open the air-cleaner filter to the fresh-air induction. Flapper valves inside the plenum opened and closed depending on intake manifold vacuum. Under high vacuum (idle and part throttle), the pair of actuators kept the flaps closed. At wide-open throttle, the resulting drop in vacuum allowed the flaps to open so the cooler and denser outside air could rush into the induction system for more power. The flaps also pop open when the engine is shut off.

Brit's hood still had the plastic intake ducts inside the NACA scoops. They are also available new from NPD. If the car has a non-functional scooped hood, remove the block-off plates.

Ram-Air was standard on '71 429-R and Boss 351 Mustangs and optional on 351 models in 1971-'72. Interestingly, at mid-year '72 and throughout '73, it was available only with the 351C two-barrel engine due to federal emissions standards.

If you're starting with a scooped hood that is non-functional, you'll need the underhood plenum, scoop ducts, air-cleaner base with filter and small lid, attaching screws, vacuum hose, and a vacuum fitting for the intake manifold. All are available as new reproductions from NPD.

Note that the air-cleaner bases for 351C and 429 engines are different; the NPD base fits 351s and 302s. Also, for '73 the 351C used an EGR spacer under the carburetor; it must be removed to allow the hood to close properly when ram-air is added. Be advised that some aftermarket aluminum intakes may raise the air cleaner too far for a proper fit.

Brit's '73 Mach is being refurbished by Restomods Plus as a fun driver, not a concours show car, so Wayne didn't concentrate on finding original fasteners or hoses. NPD's reproduction ram-air components are a great way to put function into the scoops on '71-'73 Mustangs.

National Parts Depot '71-'73
Ram-Air Parts

  • Hood (with scoops) - PN 16612-6A
  • Air cleaner assembly - PN 9600-11A (fits 351 and 302)
  • Air cleaner seal - PN 9B624-4A
  • Hood plenum - PN 16613-4B
  • Plenum mounting screws (concours) - PN 16613-4AK
  • Hood duct inserts - PN 16C630-4A