- Autolite 4100 Hard Starting
- Autolite 4100 Flooding
- Gas Dribbles Out the Discharge
- 4100 Won't Run Without Closing the Choke
The baffle you refer to is used to keep the heat in the choke thermostat. It would be nice to have the baffle, but they are often left out because they are unavailable. It isn't that hard to make one from a piece of tin.
Hi, I'm working on a 66 autolite 4100. It's a 1.12 in a 66 galaxie 500 with a 390. The carb was "rebuilt" when my neighbor bought the car. The carb is very clean and appears recently overhauled. It currently starts hard. You must hold the accelerator to the floor to get it to start. then when you shut the car off the carb dumps about 1/8" fuel on the secondary throttle plates. The float adjustments seem to be in order. However they installed a different needle and seat combination than what you sell. the needles have flat bottoms with a small pad on them. THe fast idle lever was broken on the choke, and I purchased that from you about a week ago. That helped a little but the the fuel dump on the secondaries seems to be a major issue. Any thoughts you can offer are appreciated. Thanks!
Answers:
You are flooding (getting too much gas it the float bowl).
Causes:
High fuel pump pressure (test the pressure and compare with specs from your motors manual)
Needle & seat not closing.
Float leaking and is too heavy.
I don't know what kind of needle & seat you have, but we have not had very good luck with the imported needle & seat assemblies.
Another Answer:
The needle & seat as he describes are made by XXXXX and were in most XXXXX kits. I have seen the black rubber button come out, flip over sideways and be loose in the seat. any of these conditions would cause overfilling or flooding. Another problem is the tab on the brass floats. The original OEM floats tabs were straight and extended out over the contact point on the needle. The replacement floats that are available now are bent up at 90 degree angle on the end of the tab. I straighten the tab on to get better contact. I would think that condition would be more of a problem with Tomco needle & seats. Two possibilities: the adjustment of the sec. link and if the plastic sec, arm was installed correctly (this would cause the butterflys not to close all the way) also the sec. booster (and primary) will drip fuel if the air bleeds are plugged and/or dirty. (remove booster and blow out passages in booster and main body).
If your carburetor is idling too fast and you're unable to get it to idle down, there are several potential causes for this issue. Here are some common troubleshooting steps you can take to address the problem:
Check for Vacuum Leaks: Inspect all vacuum lines and connections for any leaks or cracks. A vacuum leak can lead to an incorrect air-fuel mixture and cause the engine to idle too fast.
Idle Speed Adjustment Screw: Most carburetors have an idle speed adjustment screw. Locate this screw and try turning it counterclockwise to decrease the idle speed. Make small adjustments and observe the changes.
Stuck or Binding Throttle Linkage: Ensure that the throttle linkage is moving smoothly and not sticking or binding. A stuck throttle can keep the engine from idling down properly.
Clean or Replace Air Filter: A dirty or clogged air filter can disrupt the airflow and result in an erratic idle speed. Clean or replace the air filter as necessary.
Inspect Choke Operation: If your carburetor has a choke, make sure it's functioning correctly. An improperly functioning choke can cause high idling.
Check for Rich Fuel Mixture: A rich fuel mixture can lead to higher idling speeds. Verify that the float level and the fuel jets are set correctly in the carburetor.
Throttle Plate Adjustment: Some carburetors have an idle adjustment for the throttle plates. Make sure the plates are not opening too far, causing the engine to idle too fast.
Verify Ignition Timing: Incorrect ignition timing can affect the engine's idle speed. Ensure that the ignition timing is set to the manufacturer's specifications.
Inspect for Carburetor Clogs: Check for any clogs or debris in the carburetor jets, passages, or idle circuit. Clean the carburetor thoroughly if needed.
It could be that the throttle plates are not closing completely. This is especially suspect if you had them off of the carburetor during a rebuild.Throttle plates not closing would be the same as if you were pressing on the gas pedal a bit.
I have 1965 T-bird with a 1962 4100 carb. Would I use the 1962 specs for the carb or the 1965 specs?
Use the setting closest to the engine size that you have. Float settings depend on application, engine and often the carb number.
You can re-bush the shafts, but you should know what you are doing. It is easy to ruin the carburetor. We know a few people that can do this for you. Look at our resource page.
Disphragm, gasket, then cover.
One check ball is used in the 4100 and that is in the main discharge. If you got 2 in the carburetor kit, then put the larger one in the main discharge.
The 2nd check ball is intended for the secondary diaphragm, but it isn't necessary. You can leave it out.
A customer needed to block this port. This is what he did:
In case anyone else ever is looking for one last night I picked up a 1/8 “ brass stub, cut it short and back filled with solder. Then I ground it down and cut a slot to look like the OEM plug. Unless you look real close and notice the different color of the solder (in the center), you would never know.
Adjusting Idle Mixture Screws Doesn't Change RPM
Vacuum Leaks: If there's a vacuum leak somewhere in the system, it may affect the idle mixture and prevent any changes from having an impact on the RPM. Inspect the carburetor and intake manifold for any signs of a vacuum leak such as hissing sounds, irregular idling, or unburned fuel smell.
Carburetor Problems: The carburetor itself could be dirty or clogged, which can affect its ability to regulate the fuel and air mixture properly. This can result in unresponsiveness to adjustments. Cleaning the carburetor could help resolve this issue. I would especially look at the idle air bleeds. They are very small passages and are easily plugged. See this page.
Wrong Idle Setting: The initial idle setting might be too high, which could cause the idle circuit not to function at all. The Autolite 4100 carburetor has a separate screw for adjusting the idle speed. You may want to look into adjusting this screw to lower the idle speed and see if that makes a difference.
Fuel Pressure Issues: If the fuel pressure is too high, it can cause too much fuel to be forced past the needle and seat, which will affect the idle circuits and make the idle mixture screws unresponsive. Test for 4- 4.5 lbs
Throttle Position: If the throttle plates are not set correctly, they might not be on the idle circuit but on the main metering circuit, in which case adjusting the idle mixture screws will not change the RPM.
Too much fuel: The float level being too high could cause this type of thing.
