Jon O.
Well-Known Member
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What do these Carb hoses do?
- Thread starter Jon O.
- Start date
Jon O.
Well-Known Member
Here is the plugged off part on the carb
Jon O.
Well-Known Member
traintech55
Senior Member
Hello Jon, And welcome to the site from a fellow Indiana resident. The missing vacuum hoses are the control for your heated air intake system. Basically one hose comes from the carb to the sensor, the other runs to the control valve for the door in the air cleaner. Sometimes the valves would leak and most times they were left plugged. Only way to know is buy some hose and hook it back up. Bill
Jon O.
Well-Known Member
So if the valves leak, what will it change? Will it working make cold starting easier?
65sporty
Old Man with a Hat
If your not going to be running the car in cold weather you really don't need it, it's to provide warm air when the engine is cold.
65sporty
Old Man with a Hat
If the valve leaks you will have a vacuum leak. For better cold starting you will need to check out the choke.
The heated air system was used to compensate for leaner mixtures on startup so that the engine would run better when cold. You can get by just fine without it, it was mostly an EPA driven device that was supposed to help reduce emissions. A lot of them leaked due to the tendency of Mopar big blocks to fart back thru the carb and rupture the valve which caused a vacuum leak and defeated the whole purpose of the things. You can compensate for a dead heated air system by increasing the choke closure slightly.
Dave
Dave
You really won't notice any difference if these were connected or not. If these are disconnected and that nipple on the carb is capped, it will run as cars did before they invented this warm air addition. Mine are disconnected as well.
What it does Jon is when the eng. is cold eng. vac is allowed to open the air control valve. This draws in warm air from the exhaust manifold. This prevents carb. icing at the carb base plate. Common failures are the bad air control valve. the sensor and the upper and lower pieces of the exhaust manifold rusting away. Problems it can cause are stalling in temps under 35 degrees when cold. Attached file will give you an idea how it works.
With the oxygenated fuels that are blended today, carb icing will be a non-issue for most drivers. Wisc or Minn at 40 below maybe or maybe at altitude in the rockys. Otherwise do not worry about it.
Dave
Dave
Carb icing is very much a problem here in Indy. Jon and I living in the same city makes it relevant. I've seen it happen many times in auto repair. Carb icing is caused by high humidity and air velocity and cold air temps. Under the right conditions you can see it form. Oxygenated fuels have a greater impact on fuel burn on start up. If you don't drive in cold temps there's no problem.
I am curious, what king of low temps are we talking about? Ethanol has a really low freeze point which is why they used it for fuel system antifreeze in years past.
Dave
With high humidity temps in the 30's or less.
If your car is hard to start after sitting a couple days or longer, it is likely due to evaporating fuel from the carburetor bowl over time. Thus when cranking the engine, it will take longer for the fuel bowl to fill before it can supply fuel to start the car after sitting for a couple days or more.
In your 1972 model, I believe the evaporating fuel goes into a charcoal canister usually in the right front inner fender area, and the stored fuel is pulled back into the engine when it is running to purge the stored fuel, thus lessening emitting fuel vapors into the atomosphere. This is done to control smog in urban areas, as smog is caused by the reaction of hydrocarbons and nitrogen oxides in sunlight that combine to form smog.
In your 1972 model, I believe the evaporating fuel goes into a charcoal canister usually in the right front inner fender area, and the stored fuel is pulled back into the engine when it is running to purge the stored fuel, thus lessening emitting fuel vapors into the atomosphere. This is done to control smog in urban areas, as smog is caused by the reaction of hydrocarbons and nitrogen oxides in sunlight that combine to form smog.
Might also want to check to be sure that the choke linkage is allowing the choke to close all the way when the engine is cold. Also might want to check to be sure the heat riser is not stuck closed as this can over heat the carb and cause rapid fuel evaporation. Let the car sit overnight and remove the top of the air cleaner, cycle the throttle once full open and note the position of the choke, it should be fully closed. Now prop the choke open and look down the throat of the carb. Have a helper push down on the throttle, you should see gas squirting near the air horns. If you do not see any fuel, the carb is likely dry from the fuel evaporating. The heat riser should be checked next, grab the weight on the heat riser and be sure it rotates freely. If it is stuck, you will need to free it up, the light penetrating oil in a spray can applied to the heat riser shaft is usually all it will take. Spray it and rotate the weight until it turns freely. Obviously you need to do all of these operations with the engine off and the key out of the vehicle in case you have a kid helping.
Dave
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One item on the hard starting MIGHT be the choke valve not being able to close fully on initial start-up. With the Holley 2210 2bbls, as with the prior Stromberg WWC carbs, IF the air cleaner wing nut has been tightened too much, it will exert a pull on the center carb stud UPWARD, which will slightly re-form the air horn casting in the center (in the air cleaner stud mounting area). This can also compromise the power piston vacuum passage seal (air horn to carb main casting/float bowl), too. When that happens, it's "power mixture" all of the time, which means about 11mpg no matter what. The Carter BBD 2bbls had a more archaic (to me) air cleaner stud attachment, by observation, so no issues of this sort.
Unlike the prior Strombergs, Chrysler/Holley did come out with a "Bridge Kit" for the re-formed carb air horn. It was basically a square piece of metal going between the two center-outer carb screws, and a new center stud attached to it. There is also a thicker air horn gasket in the kit, too.
To install, remove the existing carb stud from the air horn. Remove the two carb screws needed to install it, as new longer screws should be in the kit. Remove the other carb screws to install the thicker air horn gasket. Replace the gasket, snugging down the screws to ensure location of the gasket and air horn on it. Using the supplied screws, install the "bridge" bar.
Starting with the new center screws, snug-down the car screws in a normal inside-to-outside torque sequence. Once that is done, repeat from the bridge screws outward.
The bridge should contact two raised portions in the air horn casting, pushing that area of the carb downward to remove the accumulated warpage. Once done, the choke valve should operate normally and freely.
The "hot air" air cleaner does tend to support the learner carb calibrations of the emissions control system. As noted, the main benefits might only be seen during emissions testing, rather than in normal driving in moderate-cold weather. Colder air will effectively further lean and existing mixture, with the cooler and more dense air. The warmer air from the heat stove on the exhaust manifold makes the carb think it's at least 100 degrees F ambient when it's working in cooler weather. That's what the thermostat in the air cleaner base does.
Personally, I like for mine to work if they still can. Then I know things are as they should be.
The Chrysler/Holley "Bridge Kit" can still be found on eBay Motors, sometimes. FEW people know what it is and since it is only for the Holley 2210/2245 2bbl carbs, not much activity on them, I suspect. BUT it's better than getting another carb, by observation!
Had to do these things to our '72 Newport 400-2, back when it was a "used car". How I know about it. Also went through the warped air horn situation on the '66 Chrysler with the Stromberg WWC-3 carb, making a spacer air horn gasket so the power valve would close on fast idle. The choke would operate normally, BUT enough air flow to pull fuel from the float bowl over the rear wall and further enrich the fast idle mixture, "fogging mosquitoes" in the process of just trying to keep it running (how I knew the spacer gasket had failed).
SO . . . make sure the air filter element fits correctly and don't give the wing nut that extra 1/2 turn (for good measure)!
CBODY67
Unlike the prior Strombergs, Chrysler/Holley did come out with a "Bridge Kit" for the re-formed carb air horn. It was basically a square piece of metal going between the two center-outer carb screws, and a new center stud attached to it. There is also a thicker air horn gasket in the kit, too.
To install, remove the existing carb stud from the air horn. Remove the two carb screws needed to install it, as new longer screws should be in the kit. Remove the other carb screws to install the thicker air horn gasket. Replace the gasket, snugging down the screws to ensure location of the gasket and air horn on it. Using the supplied screws, install the "bridge" bar.
Starting with the new center screws, snug-down the car screws in a normal inside-to-outside torque sequence. Once that is done, repeat from the bridge screws outward.
The bridge should contact two raised portions in the air horn casting, pushing that area of the carb downward to remove the accumulated warpage. Once done, the choke valve should operate normally and freely.
The "hot air" air cleaner does tend to support the learner carb calibrations of the emissions control system. As noted, the main benefits might only be seen during emissions testing, rather than in normal driving in moderate-cold weather. Colder air will effectively further lean and existing mixture, with the cooler and more dense air. The warmer air from the heat stove on the exhaust manifold makes the carb think it's at least 100 degrees F ambient when it's working in cooler weather. That's what the thermostat in the air cleaner base does.
Personally, I like for mine to work if they still can. Then I know things are as they should be.
The Chrysler/Holley "Bridge Kit" can still be found on eBay Motors, sometimes. FEW people know what it is and since it is only for the Holley 2210/2245 2bbl carbs, not much activity on them, I suspect. BUT it's better than getting another carb, by observation!
Had to do these things to our '72 Newport 400-2, back when it was a "used car". How I know about it. Also went through the warped air horn situation on the '66 Chrysler with the Stromberg WWC-3 carb, making a spacer air horn gasket so the power valve would close on fast idle. The choke would operate normally, BUT enough air flow to pull fuel from the float bowl over the rear wall and further enrich the fast idle mixture, "fogging mosquitoes" in the process of just trying to keep it running (how I knew the spacer gasket had failed).
SO . . . make sure the air filter element fits correctly and don't give the wing nut that extra 1/2 turn (for good measure)!
CBODY67
Jon O.
Well-Known Member
Here is the fully cold carb already pumped for starting. The plate is fully closed. The car sat for 17 years and I dont think the carb was rebuilt anytime recently, Do you think that the float bowl may have a slow leak? It has auful gas mileage.
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70bigblockdodge
Old Man with a Hat
Definitely for icing. 40° and good humidity level, low rpm, decent pedal pressure is a recipe for icing. That POS Holley is a problem. Fuel evaporating from float bowls is a product of modern gasoline, they no longer add a surface tensioner to it because modern fuel system is not open to the air.
Jon O.
Well-Known Member
Should I screw around with adjustments on the carb or just leave them alone?
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