Cold Air Intake Duct

[Michael O’Harran]

I finally got my cold air intake duct for my 72’ and will use it in junction with my ram air kit. I can find any number of pictures, diagrams, tutorials and videos about ram air functionality, but I am looking for the understanding of how this duct gets fed it’s forced fresh air. I put it in place and the opening at the grill points to the ground not forward through the grill like I would have thought. My only guess is the front chin spoiler feeds the airflow up and that’s how it catches it? Anyone have insight on its actual design?

 

[LloydB]

Can you provide pictures? Cold air just moves the intake port somewhere outside the hot engine bay, whereas "ram air" intakes are somewhere that the wind pressure "forces" air into the breather. Technically the ram air hood could be called a cold air intake as well.

 

[Michael O’Harran]

I’m talking about part 9A624

 

[Steve McMahan]

While not an engineer that specializes in air pressure dynamics, my assumption is that as a car moves through the air, quite of bit of pressure builds up in front of the grill, front fascia, etc. By pointing the inlet down, it appears they are taking advantage of that air buildup and at the same time, not picking up moisture that could be caught my a megaphone style of inlet.

 

[LloydB]

Ah, the factory style fresh air intake. The downturn is to keep bugs, birds, sand and Chrystler products from getting rammed down the tube.

 

[Michael O’Harran]

Ah, the factory style fresh air intake. The downturn is to keep bugs, birds, sand and Chrystler products from getting rammed down the tube.

And there’s enough pressure to still force into the duct with the downward opening?

 

[Hemikiller]

It's not intended to be a ram air system, but to supply the air cleaner with cooler outside air so that the temp sensor in the air cleaner can better regulate the air temperature entering the carburetor.

 

[Doug's 73 Mach1]

73s used the air ducting in the figure to draw cooler air into the intake than would have the case without the ducting and flexible connection. Prior years drew the air from under the hood where the air is typically warmer. Cooler air is typically more dense and better for performance. This ducting arrangement also likely played a roll in reduced emissions as each year the allowable emissions got tighter and tighter, 73 being tighter than prior years. This ducting arrangement was not known as "ram air", rather,

The term "ram air" was used for cars with the ram air option, an air ducting system mounted to the underside of the hood that let cooler air into the two intake ducts on top of the NACA type hood into the air cleaner that was sealed to an under hood plenum. This is known as "ram air' because air is forced into the ducts by the forward motion of the car. The plenum had two vacuum actuated flaps in the hood inlets that would open on hard acceleration (lower manifold vacuum condition) letting air be forced (rammed) in and close shutting air off when higher vacuum resumed under non hard acceleration conditions. When closed the intake air came only from the ducting in the first paragraph above or the warm air ducking connected to the outside of passenger side exhaust manifold. Warn air was needed when the engine was cold to help faster warmups and get the choke to open sooner, this too likely helping to reduce emissions. There is a vacuum actuated flap in the air cleaner snorkel controlled by a temperature vacuum switch mounted to the underside of the air cleaner. When warm enough, the flap would be activated via vacuum letting cool air in from the ducting in the first paragraph above. When cold, the switch would block vacuum to the actuator and keep warmer air coming into the underside of the snorkel from the exhaust manifold duct.

Hope this is helpful for you.

 

[Michael O’Harran]

73s used the air ducting in the figure to draw cooler air into the intake than would have the case without the ducting and flexible connection. Prior years drew the air from under the hood where the air is typically warmer. Cooler air is typically more dense and better for performance. This ducting arrangement also likely played a roll in reduced emissions as each year the allowable emissions got tighter and tighter, 73 being tighter than prior years. This ducting arrangement was not known as "ram air", rather,

The term "ram air" was used for cars with the ram air option, an air ducting system mounted to the underside of the hood that let cooler air into the two intake ducts on top of the NACA type hood into the air cleaner that was sealed to an under hood plenum. This is known as "ram air' because air is forced into the ducts by the forward motion of the car. The plenum had two vacuum actuated flaps in the hood inlets that would open on hard acceleration (lower manifold vacuum condition) letting air be forced (rammed) in and close shutting air off when higher vacuum resumed under non hard acceleration conditions. When closed the intake air came only from the ducting in the first paragraph above or the warm air ducking connected to the outside of passenger side exhaust manifold. Warn air was needed when the engine was cold to help faster warmups and get the choke to open sooner, this too likely helping to reduce emissions. There is a vacuum actuated flap in the air cleaner snorkel controlled by a temperature vacuum switch mounted to the underside of the air cleaner. When warm enough, the flap would be activated via vacuum letting cool air in from the ducting in the first paragraph above. When cold, the switch would block vacuum to the actuator and keep warmer air coming into the underside of the snorkel from the exhaust manifold duct.

Hope this is helpful for you.

Very educational. It’s like with each step in the restoration, I am forced to pause and learn more in depth details about the finer details on my car. I love it. Thanks.

 

[mrgmhale]

It's not intended to be a ram air system, but to supply the air cleaner with cooler outside air so that the temp sensor in the air cleaner can better regulate the air temperature entering the carburetor.

Yep, dead on (HemiKiller & Doug's 73 Mach 1)! And, for the "real" Ram Air setup with the underhood plenum where outside cooler air is fed to the carb, this is not a substitute for, or even a junior version of, a forced air induction system (turbocharging or supercharging). Any outside, cooler air coming from the cold air or Ram Air systems that is in excess of what the carburetor allows to pass through it, gets dumped out the Air Filter Housing inlet. I have not ever seen demonstrable evidence that Ram Air does anything significant with engine performance. It does let the sound of the carburetor being at Wide Open Throttle become much more evident, which may give the impression of greater performance. But, in reality, especially at street speeds, all the Ram Air system does is get cooler outdoor air into the carburetor - which does have some benefit to performance, but nothing all that terrific. But, if nothing else it looks great, mean, with much the same effect on performance as racing stripes provide. That said, I happen to like racing stripes and tasteful bling (hood hold downs, rear window louver slats, front spoiler, rear spoiler/wing, nice wheels and tires. When did the restoration of our 73 Mach 1, which already had the front spoiler, hood blackout, and Ram Air (it had the NACA/NASA hood, I just opened up the scoop blocking plates, added the air plenum, and activated the vacuum doors). I added the rear window louver slats, rear wing, and Dzus Hood Hold Down units. Why? Because I really do like the full look of a Mach 1 from the early First Generation Mustangs - a lot. So what if the stripes, spoilers, rear wing, and Ram Air don;t do anything of substance, epecially at local roadway speeds. If nothing else it looks good, even standing still. Oh, nostalgia!

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[MaddMike]

Can somebody help me identify and or find a piece. I want to remove my air cleaner cold air intake - it is worthless. I am looking for a cold air intake cap/cover like the one you can see on the 2nd image. Does anyone know where I can find one or something similar and what is it even called?

 

[Sheriff41]

I've been thinking about making something similar. I'm thinking of getting a used snorkel, cutting it off and welding it closed. If I do I'll let you know.

 

[jasonwthompson]

I seem to recall an article long ago about a Boss 302 with and without a shaker, and there was a difference in rear wheel HP, though slight. All "Ram Air" Ford designs are basically cold air intakes, although the Galaxie Thunderbolts that had one headlight removed may have been more of a ram air.