Ram Air Feature Question

[Wolverine]

In summary of this thread:

 


As I am not a fortunate child with the RAM AIR feature, I was curious regarding the air cleaner assembly.

 


1. Does the air cleaner assembly have just the 1 snorkel, or does it have a second air inlet not related to the ram air?

RAM AIR air cleaner assembly has a single snorkel. This snorkel has a vacuum operated valve on it that is normally open. During cold startup, as determined by a thermostatic vacuum valve on the bottom of the air cleaner, vacuum operates the valve, and only air that is warmed by the exhaust manifold is allowed to enter the carburetor. Once warm, the vacuum to the valve is removed, the valve opens and the snorkel is venting fresh, unwarmed air to the engine.

The RAM AIR ducts themselves are also NORMALLY OPEN. On cold startup, a vacuum valve(controlled by a thermostic vacuum valve) closes the ducts at the inlet. They will remain open if the engine is off[/b], or if BOTH of the following conditions are met:

 


1. Thermostatic valve detects a warm condition.


2. Decrease in manifold vacuum pressure due to open throttle condition.

 


My 351 4V air cleaner has a full chrome lid with 351-4V decal, 1 inlet with a snorkel, and a 2nd inlet with a vacuum operated gate to allow additional air in under full throttle. Was this type of air cleaner base used in RAM AIR.

 


No, see above.

 


I have seen original labels on these chrome lids with the designation 351-4V, 351-CJ and 351-HO(Is it just me, or did HO mean high output long before it became fashionable in the ghetto).

 


2. Where does WATER that enters into the ram air go?

 


Nobody knows...at least not yet. Maybe that explains the rusty bases on ram air air cleaners?

 

[Mister 4x4]

The Ram Air is more or less a two-piece solution.

There's the plastic plenum attached to the hood, which directs are from the ducts to the portion of the plenum that mates up to the air cleaner.

The air cleaner is a specialized unit that seals to the underside of the ram air plenum when the hood is closed. The design is pretty much like having an oversized 'pan' with a normal sized air filter element inside, which allows for more airflow around the filter element. No 'second' snorkel for extra air that I'm aware of - just the open 'top' sealed to the underside of the hood plenum.

There are three vacuum actuators that direct/redirect air flow (1 each for the hood ducts located on the hood itself, and 1 for the snorkel on the air cleaner). During normal driving and idling, the actuator on the air cleaner is open, with the 2 on the hood ducts closed. When sufficient throttle is applied, the rise in vacuum opens the actuators at the hood ducts and closes the snorkel's actuator.

Not a very detailed explanation, but that with a couple of Google images should help explain it all (I just used 1971 Mustang Ram Air) and it pulled up a bunch of pictures of the plenum and air cleaner installed on the engines.

Hope that helps!

 

[OMS]

Eric, the door on the snorkle is for cold start / choke only.

After the eng warms up it is always open.

The air cleaner with diverter door on LH side is a 72 - 351 CJ air cleaner

or

There was also a boss 302 air cleaner with the dirverter door for non shaker cars

 

[Mister 4x4]

Eric, the door on the snorkle is for cold start / choke only.

After the eng warms up it is always open.

The air cleaner with diverter door on LH side is a 72 - 351 CJ air cleaner

or

There was also a boss 302 air cleaner with the dirverter door for non shaker cars

Well, there ya go! Thanks for clearing that up - I did not know that. I always figured it ran on engine compartment air until it needed to consume mass quantities, then opened the ram air ducts for cooler air...

Good to know!

 

[Wolverine]

Little type there...

Where does the WATER go if it runs up the ram air?

 

[71mach351]

When sufficient throttle is applied, the rise in vacuum opens the actuators at the hood ducts and closes the snorkel's actuator.

I thinks it just the opposite. At idle and low throttle vac is high and the vac hold the hood ducts closed. At high throttle vac drops and the ducts open. I don't have my hood ducts hooked to to a vac source and they are always open. As soon as I plug them in they snap closed.

 

[1971mach1]

Little type there...

Where does the WATER go if it runs up the ram air?

I think that's why the ram air ducts had vacuum flaps, so the water wouldn't get in when you're just cruzing. They open only when you give it more throttle. The engine likes some water vapor, it actually increases octane. That's the purpose of water injection systems.

 

[Jim and Jutta]

I think that's why the ram air ducts had vacuum flaps, so the water wouldn't get in when you're just cruzing. They open only when you give it more throttle. The engine likes some water vapor, it actually increases octane. That's the purpose of water injection systems.

The few times I got caught in the rain I did notice the car seemed to run better...or maybe the rear wheels were breaking traction more frequently for another reason?

 

[Mister 4x4]

When sufficient throttle is applied, the rise in vacuum opens the actuators at the hood ducts and closes the snorkel's actuator.

I thinks it just the opposite. At idle and low throttle vac is high and the vac hold the hood ducts closed. At high throttle vac drops and the ducts open. I don't have my hood ducts hooked to to a vac source and they are always open. As soon as I plug them in they snap closed.

To-may-to, to-mah-to. Sorry - I meant what you said... and probably should've said, "increase" in vacuum instead of ''rise in vacuum." But you understood where I was coming from, since we pretty much said the same thing.

Dang... picky people. Sheesh.

Little type there...

Where does the WATER go if it runs up the ram air?

I can't say for sure, but I would suspect there are some small drain holes somewhere in the plenum, or maybe in the air cleaner pan or something. Having the water make it all the way to the air filter is only going to resort to a wet air filter - which would actually restrict airflow - not so much atomized water vapor 'hydrocharging' the air/fuel mixture.

 

[Wolverine]

I just updated the first post on this thread to reflect the information gathered.

Let's see if I will be able to find it in 6 months.

 

[71MACH-1]

it appears my snorkel open only when I give it gas....... when I am idleing, it is closed....please help

 

[Mister 4x4]

it appears my snorkel open only when I give it gas....... when I am idleing, it is closed....please help

Sounds like you need a new temperature-controlled vacuum switch. That, or the vacuum lines are run incorrectly to operate in the manner Don described.

 

[71MACH-1]

Do you mean the vacuum on the snorkel?

 

[Mister 4x4]

Do you mean the vacuum on the snorkel?

Yes and no - the vacuum on the snorkel should close when the ram-air ducts open, and open when the ducts close... that much I know for sure.

The temperature-controlled vacuum switch is a device that is on one of the water pump outlets with multiple vacuum outlets. I remember someone saying it was for the vacuum advance on the distributor, but I can see where it would work for the ram-air as well.

My ram-air isn't installed, or even complete yet, so I'll defer to the greater knowledge of others to offer better advice.

 

[OMS]

Plenum flappers

Engine off - always open

Engine running closed - only open when loss of vacuum occurs from full throttle use - temperature does NOT matter

Snorkel flapper

NOTE snorkel flapper does NOT care what plenum flappers are doing.

Only used for cold start / engine warm up, otherwise snorkel door should always be open - Only closed when vacuum applied from cold start bi - metal sensor located on bottom of air cleaner.

Snorkel door only switches where air is drawn in from - end of snorkel OR bottom of snorkel off the exhaust manifold.

When vacuum is applied the door switches to cold position - it draws warm / hot air off the exhaust manifold to help the car run while engine is cold.

A lot of people do not have a working sensor - or use the snorkel door since the cars don't get used in the winter.

Plus if you don't have exhaust manifolds, the heat riser and tube assembly it won't draw hot air anyway.

Hope this helps

 

[mrbill4]

Plenum flappers

Engine off - always open

Engine running closed - only open when loss of vacuum occurs from full throttle use - temperature does NOT matter

Snorkel flapper

NOTE snorkel flapper does NOT care what plenum flappers are doing.

Only used for cold start / engine warm up, otherwise snorkel door should always be open - Only closed when vacuum applied from cold start bi - metal sensor located on bottom of air cleaner.

Snorkel door only switches where air is drawn in from - end of snorkel OR bottom of snorkel off the exhaust manifold.

When vacuum is applied the door switches to cold position - it draws warm / hot air off the exhaust manifold to help the car run while engine is cold.

A lot of people do not have a working sensor - or use the snorkel door since the cars don't get used in the winter.

Plus if you don't have exhaust manifolds, the heat riser and tube assembly it won't draw hot air anyway.

Hope this helps

that's exactly how mine is set up including no door on the snorkel