Manifold heat riser
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Manifold heat riser
I have a 1973 300ci.
Simple question... I hope.
What position is the outer spring/shaft supposed to be in (looking at the rear of the engine) when the engine is warmed up. I don't want to drive around in the heat with the manifold heater on. Not real great on gas that way!
Thanks in advance
Simple question... I hope.
What position is the outer spring/shaft supposed to be in (looking at the rear of the engine) when the engine is warmed up. I don't want to drive around in the heat with the manifold heater on. Not real great on gas that way!
Thanks in advance
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Yes it freely rotates. I hooked it with the counterweight in the "up" position, (full clockwise) using a small tight spring. So I can assume that the valve is in the closed (NOT heating the intake manifold) position, right?
Thanks.
Thanks.
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From: Boise, Idaho
If the riser is freely rotating, why do you want to lock it in place? It closes automatically when the engine warms up, cutting off manifold heat to the carburetor.
The position it's in when the engine is cold and at rest is going to be fully open, so if you rotated it and locked it in place, then yeah, you have it closed.
The position it's in when the engine is cold and at rest is going to be fully open, so if you rotated it and locked it in place, then yeah, you have it closed.
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The valve rotates freely, but the bi-metallic spring is broken, which is common, that keeps it in the open position. Since it's only real purpose is to prevent carburetor icing and that only happens when conditions are right. The van is an icecream truck-to-be so I don't think I'll be worring much about that.
Thank you for your information... it will help keep ice cream prices down!
Thank you for your information... it will help keep ice cream prices down!
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From: Northern Virginia, USA
Not just icing, but driveability in general, especially in cold weather. That hot spot on the bottom of the intake keeps fuel atomized when not in a high-vacuum situation. Loose the heat, and you'll get mixture problems and terrible running under any load, especially at low speeds/throttle, when you have low airflow speeds in the intake manifold. Fuel just drops out of suspension and puddles in the intake.
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From: Boise, Idaho
I was about to mention that, but you beat me to it.
If you're interested, Rockauto.com has an entire heat riser replacement kit for $70 (spring, plate, etc.). I wonder if it's possible to just source the spring from Ford?
If you're interested, Rockauto.com has an entire heat riser replacement kit for $70 (spring, plate, etc.). I wonder if it's possible to just source the spring from Ford?
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From: Petal Miss.
This should help, if you haven't got it figured out already.<a href="http://s809.photobucket.com/albums/zz12/futlocker/?action=view¤t=IMG_3788.jpg" target="_blank"><img src="http://i809.photobucket.com/albums/zz12/futlocker/IMG_3788.jpg" border="0" alt="Hot air valve picture"></a>
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I appreciate the picture, but now I'm more confused. The picture shows that when the plate is in the vertical position, the valve is open and the heat is off. When in the horizontal position the valve is closed and the heat is on.
I'm confused by this because when the valve is in the vertical position it exposes the bottom of the intake to exhaust heat. (when cold). But the picture is labeled valve open HEAT OFF. When the valve is in the horizontal position the valve is closed and the exhaust heat is then diverted away from the bottom of the intake. This should be heat off.
Am I missing something here? Shouldn't it be vice versa?
I'm confused by this because when the valve is in the vertical position it exposes the bottom of the intake to exhaust heat. (when cold). But the picture is labeled valve open HEAT OFF. When the valve is in the horizontal position the valve is closed and the exhaust heat is then diverted away from the bottom of the intake. This should be heat off.
Am I missing something here? Shouldn't it be vice versa?
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From: Petal Miss.
Here is another picture
<a href="http://s809.photobucket.com/albums/zz12/futlocker/?action=view¤t=6e9b_1.jpg" target="_blank"><img src="http://i809.photobucket.com/albums/zz12/futlocker/6e9b_1.jpg" border="0" alt="Photobucket"></a>
<a href="http://s809.photobucket.com/albums/zz12/futlocker/?action=view¤t=6e9b_1.jpg" target="_blank"><img src="http://i809.photobucket.com/albums/zz12/futlocker/6e9b_1.jpg" border="0" alt="Photobucket"></a>
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OK. That is the vertical position, the valve is open allowing the hot exhaust gasses to contact the bottom of the intake, just under the carb. Once the engine warms up, that closes into the horizontal position and diverts the gasses away from the intake manifold, allowing for a cooler air/fuel mixture and better economy. Or is there something I'm missing? Is the plate covering a port in the exhaust manifold or something?
The reason I'm confused goes back to when I had a 1950 Dodge Pick-up. It had a similar setup. These were "show vehicles" and the majority of the owners I chattrd with would take the manifolds apart and weld the valve in the hoizontal position to keep it from rattling or sticking open causing very poor gas mileage.
The reason I'm confused goes back to when I had a 1950 Dodge Pick-up. It had a similar setup. These were "show vehicles" and the majority of the owners I chattrd with would take the manifolds apart and weld the valve in the hoizontal position to keep it from rattling or sticking open causing very poor gas mileage.
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From: Petal Miss.
When in the horizontal the valve directs the full exhaust to the base of the intake.
As it heats up it turns to vertical, opening the way to the exhaust.
The intake still receives heat just not as much, for now the way to the exhaust is open.
Because of the constant heat supply, I was still having trouble with mine boiling the fuel in the carb after shut down.
I made a heat shield to absorb the heat instead of the carb no more problem with the carb getting cooked.
Vincent
<a href="http://s809.photobucket.com/albums/zz12/futlocker/?action=view¤t=IMG_3782.jpg" target="_blank"><img src="http://i809.photobucket.com/albums/zz12/futlocker/IMG_3782.jpg" border="0" alt="heat shield"></a>
<a href="http://s809.photobucket.com/albums/zz12/futlocker/?action=view¤t=IMG_3780.jpg" target="_blank"><img src="http://i809.photobucket.com/albums/zz12/futlocker/IMG_3780.jpg" border="0" alt="Photobucket"></a>
As it heats up it turns to vertical, opening the way to the exhaust.
The intake still receives heat just not as much, for now the way to the exhaust is open.
Because of the constant heat supply, I was still having trouble with mine boiling the fuel in the carb after shut down.
I made a heat shield to absorb the heat instead of the carb no more problem with the carb getting cooked.
Vincent
<a href="http://s809.photobucket.com/albums/zz12/futlocker/?action=view¤t=IMG_3782.jpg" target="_blank"><img src="http://i809.photobucket.com/albums/zz12/futlocker/IMG_3782.jpg" border="0" alt="heat shield"></a>
<a href="http://s809.photobucket.com/albums/zz12/futlocker/?action=view¤t=IMG_3780.jpg" target="_blank"><img src="http://i809.photobucket.com/albums/zz12/futlocker/IMG_3780.jpg" border="0" alt="Photobucket"></a>
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I got it now. Thanks!
I like what your doing with your 4.9. The shield is a great idea plus it looks well done too!
I'm thinking of getting an aftermarket air cleaner for mine too. I have an old oil bath air cleaner. Not really necessary for what I'm doing and cleaning it can be a mess too.
Bob
I like what your doing with your 4.9. The shield is a great idea plus it looks well done too!
I'm thinking of getting an aftermarket air cleaner for mine too. I have an old oil bath air cleaner. Not really necessary for what I'm doing and cleaning it can be a mess too.
Bob
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