How To Install Ram Air

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... 

   

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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

Wayne says the plenum installation...        read full caption Wayne says the plenum installation can be done with the hood on the car but it's easier with the hood removed and lying upside-down on a workbench.	The plenum openings slide...        read full caption The plenum openings slide over the intake ducts in the scoops.	NPD offers a concours mounting...        read full caption NPD offers a concours mounting kit with the correct screws for attaching the plenum to the hood. For this non-concours installation, Wayne used gas-tank screws from AMK, PN F-357.
Vacuum hoses run from the...        read full caption Vacuum hoses run from the actuator valves to a plastic T-fitting at the base of the plenum. Wayne used tubing brackets, typically used for fuel lines, from a local auto-parts store to secure the hose to the plenum's edges. The single hose from the T-fitting will go to a fitting in the intake manifold as a vacuum source.	Here's the completed plenum...        read full caption Here's the completed plenum installation looking good on the freshly painted underhood.	With the air-cleaner assembly...        read full caption With the air-cleaner assembly painted the correct Ford Corporate Blue, Wayne slips the rubber hood seal over the edge of the air-cleaner base. A small bead of sealer helps hold it in place.
The smaller diameter air-cleaner...        read full caption The smaller diameter air-cleaner lid covers just the air cleaner, leaving the outside open for the fresh-air induction from the hood plenum. Brit's '73 still had its air cleaner; reproductions for 351s and 302s are available from NPD.	With the plenum mounted to...        read full caption With the plenum mounted to the hood and the air cleaner in place, the hood can be installed on the car.	Here's the completed installation,...        read full caption Here's the completed installation, with the exception of the still-missing air-cleaner snorkel. Wayne closed the hood carefully to make sure the plenum and air cleaner align. For a number of reasons, from carburetor spacers to taller aftermarket intakes, the air cleaner may sit too high. You'll have to make adjustments based on your Mustang's combination of parts.
A bug's eye view shows the...        read full caption A bug's eye view shows the open flap, a position it assumes when there's no intake vacuum-either wide-open throttle or engine off.	Wayne searched his parts bin...        read full caption Wayne searched his parts bin for an intake manifold vacuum fitting. He found this one. Once the top is capped off, the small nipple fitting will supply engine vacuum to the plenum actuators.