Stock Air Intake "Flap"
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Freshman User
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Stock Air Intake "Flap"
First, a description:
My '68 250 with a 360 2bbl has the stock filter housing w/ intake duct. In the duct is a flap actuated by vacuum. The flap either lets air in through the mouth (or horn) of the duct or through an opening in the bottom of the duct (of apparently the same size). The vacuum actuator has a rod which goes through an armature clip on the flap to operate it. It appears I must be missing a clip or something because the vacuum actuated rod is not actually attached to the armature clip - it can slide back and forth without actuating the flap. The flap is currently stuck in the up position so air enters through the bottom of the intake duct.
Second, questions:
1) What is this thing?
2) I have detached the vacuum line due to vibration and buzzing from this contraption. If I leave it off, which position should the flap be in?
3) What piece am I missing, where do I get it, and is there some sort of adjustment or setting so when I put this back together so it operates correctly?
I know I can go with one of these open filters, but would prefer to keep the truck as stock a possible.
Thanks!
My '68 250 with a 360 2bbl has the stock filter housing w/ intake duct. In the duct is a flap actuated by vacuum. The flap either lets air in through the mouth (or horn) of the duct or through an opening in the bottom of the duct (of apparently the same size). The vacuum actuator has a rod which goes through an armature clip on the flap to operate it. It appears I must be missing a clip or something because the vacuum actuated rod is not actually attached to the armature clip - it can slide back and forth without actuating the flap. The flap is currently stuck in the up position so air enters through the bottom of the intake duct.
Second, questions:
1) What is this thing?
2) I have detached the vacuum line due to vibration and buzzing from this contraption. If I leave it off, which position should the flap be in?
3) What piece am I missing, where do I get it, and is there some sort of adjustment or setting so when I put this back together so it operates correctly?
I know I can go with one of these open filters, but would prefer to keep the truck as stock a possible.
Thanks!
Elder User
Joined: Mar 2004
Posts: 976
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From: SOUTH CAROLINA
that is the flap for the heat riser. there is supposed to be a tube coming from the exhaust manifold to the bottom of the inlet on the air cleaner. it helps to warm the air on cold starts.the flap also uses heat to open up after it gets warm so its in the horizontal position to draw air from the engine compartment. hope that helps. steve
Cargo Master
Joined: Apr 2004
Posts: 2,574
Likes: 4
From: Golden, CO
When you go for parts, it'll be called a thermal air cleaner (TAC). It's a big benefit for people who live in colder climates. By regulating intake air temperature, you prevent ice formation in the carb, and promote fuel vaporization in cold weather conditions.
The basic components include:
Some type of sheet metal shroud over the same side exhaust manifold. This may or may not have the duct that connects with the air cleaner.
A vacuum motor (the part you asked about).
Inside the air cleaner should be a reed type, thermal vacuum switch. This should have one hose to the vacuum motor, another hose to manifold vacuum.
Your best bet for the shroud over the exhaust manifold is a junk, uh, automotive parts recycling center. You may get lucky and find a complete system. I have swapped just the snorkel to avoid messing with the vacuum motor.
Your local auto parts store should have the thermal vacuum switch and vacuum motor if you need new ones. They also have the flexible duct found on newer vehicles.
Happy hunting, Mike
The basic components include:
Some type of sheet metal shroud over the same side exhaust manifold. This may or may not have the duct that connects with the air cleaner.
A vacuum motor (the part you asked about).
Inside the air cleaner should be a reed type, thermal vacuum switch. This should have one hose to the vacuum motor, another hose to manifold vacuum.
Your best bet for the shroud over the exhaust manifold is a junk, uh, automotive parts recycling center. You may get lucky and find a complete system. I have swapped just the snorkel to avoid messing with the vacuum motor.
Your local auto parts store should have the thermal vacuum switch and vacuum motor if you need new ones. They also have the flexible duct found on newer vehicles.
Happy hunting, Mike
Posting Legend
Joined: Sep 2001
Posts: 30,255
Likes: 37
Get the duct that goes to the radiator support also. That brings in cold outside air rather than hot air from under the hood. You can buy the flexible tube at most parts stores. The tube to the exhaust stove is a silver tube. The tube for the cold air intake is black.
The warm air eliminates carb icing which can happen even in southern states if conditions are right.
The warm air eliminates carb icing which can happen even in southern states if conditions are right.
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Freshman User
Joined: Aug 2005
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Originally Posted by Hypoid
Inside the air cleaner should be a reed type, thermal vacuum switch. This should have one hose to the vacuum motor, another hose to manifold vacuum.
At some point someone must have stripped the system, so now I'm getting an idea of what's missing. The operation of the system makes sense now that you all have explained it to me.
Does anyone have any pics of the correct setup in their gallery?
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