[Bcrandell]

Ok so with the car running and possibly driving, I found a mew issue. The car idles fantastic but when I shift it into gear, it Boggs down and did die until I added more transmission fluid. But now it just bogs down and the gen light comes on until I put the car pack in park or give it some RPMs. I figured it might be the lack of transmission fluid but I added enough for it to be inbetweem the full and fill lines. So I'm not to sure what I'm missing. Any suggestions?

 

[GeoffTheGiraffe]

Sounds like carb/ general tuning is needed. What carburetor is on it right now? That way we can help you out better

Could be a combination of too low idle speed for an auto, lean idle mixture setting, incorrect timing, worn Plugs/ignition system

I'd check the timing is in spec, pick up a vacuum gauge and check how much you're pulling at idle. You can then set your idle mix screws to the highest steady vacuum reading and set your idle speed which I forget what it should be for an automatic in park vs drive

 

[Bcrandell]

Sounds like carb/ general tuning is needed. What carburetor is on it right now? That way we can help you out better

Could be a combination of too low idle speed for an auto, lean idle mixture setting, incorrect timing, worn Plugs/ignition system

I'd check the timing is in spec, pick up a vacuum gauge and check how much you're pulling at idle. You can then set your idle mix screws to the highest steady vacuum reading and set your idle speed which I forget what it should be for an automatic in park vs drive

So I'm working with a with a 2 barrel autolite 2100. I currently have the air/fuel mixture set to stock. The acceleration screw is set so the idle runs at just below 1,000 RPMs. I do have a vaccume/fuel pump tester from my dad's old tool box but I'm not sure where to hook it up to actually test the vaccume. I should also check the dwell setting to see how my points are doing.

 

[cougar70]

Don't add any more transmission fluid. That has nothing to do with it.

 

[Bcrandell]

Don't add any more transmission fluid. That has nothing to do with it.

I don't intend to. I busted a hose when I drove the car for a test drive and lost a lot so the levels are exactly where they should be. But that's why I was adding trans fluid.

 

[Clay_in_ABQ]

You need to check the usual things (overall health and tune): timing (with vacuum advance disconnected and the hose plugged), idle mix (using a vacuum gauge), check points for pitting or just worn out, plugs for wear or sooting, plug wires, cap and rotor. You might also have a vacuum leak. My guess is everything needs to be touched.

 

[Roxshot]

I had a similar problem with my 69 - it turned out to be a vacuum leak. Double check you vac lines with some carb cleaner.

 

[Bcrandell]

You need to check the usual things (overall health and tune): timing (with vacuum advance disconnected and the hose plugged), idle mix (using a vacuum gauge), check points for pitting or just worn out, plugs for wear or sooting, plug wires, cap and rotor. You might also have a vacuum leak. My guess is everything needs to be touched.

I can check off the points, distributor cap, rotar, spark plug wires, and condenser. I haven't really touched anything related to the vaccume yet. I've only ever adjusted the timing with the vaccume advance connected so if having that off can help properly adjust it, I'll do that. But I also have a vaccume gauge that I'll throw on to see how that's going. I'm just not to sure where to connect it.

 

[Bcrandell]

I had a similar problem with my 69 - it turned out to be a vacuum leak. Double check you vac lines with some carb cleaner.

If it is a vaccume leak, how did you stop it?

 

[Jazzmeister]

1000 RPM is too fast for your curb idle. Ford specified almost half that for the idle speed (in drive). If that’s where you are idling, I’ll bet you have your timing set lower than it might appear at “idle”. At that speed, you are almost certainly getting some advance from centrifugal and vacuum sources. Then when you put it in drive, the normal RPM drop from putting a load on the engine is accentuated by the drop in spark advance, further bogging the engine to a near stall point. If you have a timing light, watch what happens to the timing marks when the car is in gear. If everything is adjusted correctly, this should not change (or at least it should not drop below your intended base timing). Set the idle mixture at the lowest possible idle speed the car will run. If you do not have the throttle blades fully closed, you are not truly on the idle circuit, and you can’t adjust the idle fuel mixture correctly. Curb idle should be around 500RPM (block wheels, parking brake engaged). Set the timing and idle mixture this way. If it won’t go that low, I would look for a vacuum leak. In improperly adjusted choke can also prevent your idle speed screw from being backed out.

 

[Bcrandell]

1000 RPM is too fast for your curb idle. Ford specified almost half that for the idle speed (in drive). If that’s where you are idling, I’ll bet you have your timing set lower than it might appear at “idle”. At that speed, you are almost certainly getting some advance from centrifugal and vacuum sources. Then when you put it in drive, the normal RPM drop from putting a load on the engine is accentuated by the drop in spark advance, further bogging the engine to a near stall point. If you have a timing light, watch what happens to the timing marks when the car is in gear. If everything is adjusted correctly, this should not change (or at least it should not drop below your intended base timing). Set the idle mixture at the lowest possible idle speed the car will run. If you do not have the throttle blades fully closed, you are not truly on the idle circuit, and you can’t adjust the idle fuel mixture correctly. Curb idle should be around 500RPM (block wheels, parking brake engaged). Set the timing and idle mixture this way. If it won’t go that low, I would look for a vacuum leak. In improperly adjusted choke can also prevent your idle speed screw from being backed out.

Ok sorry for the pause but I had some time to work on the car. So I first noticed that my RPM reader is not working correctly which makes a lot of sense in my head. I also checked the vaccume and I couldn't get the hose from the gauge to sit comfortably on the fittings but that's because my vaccume advance line is metal on not a hose. But it read 10 PSI and went down when I reved the engine. Lastly, I tried adjusting the idle mixture screws and ended up with the fuel mixture all the way down with no change. I haven't tried the air mixture yet but I know I'm not that great with carbs but I'm pretty sure that's not suppost to happen.

 

[Jazzmeister]

Ok sorry for the pause but I had some time to work on the car. So I first noticed that my RPM reader is not working correctly which makes a lot of sense in my head. I also checked the vaccume and I couldn't get the hose from the gauge to sit comfortably on the fittings but that's because my vaccume advance line is metal on not a hose. But it read 10 PSI and went down when I reved the engine. Lastly, I tried adjusting the idle mixture screws and ended up with the fuel mixture all the way down with no change. I haven't tried the air mixture yet but I know I'm not that great with carbs but I'm pretty sure that's not suppost to happen.

If you are idling at 1000 or more RPM, the idle mixture screws will have minimal to no effect on it running, because you are getting air and fuel through the transfer and main power circuits. The idle mixture screws adjust the fuel allowed to be pulled from under the closed, or mostly closed throttle blades. Air comes from the idle air bleeds that are part of the booster venturi assembly. There is not a separate air screw, but you have two idle mixture screws, one for each bore of your carburetor. The air is pre-determined by the air bleeds and whatever can be drawn through a slightly cracked open throttle plate. You are adjusting the fuel to match that air at the correct ratios. In order to do that, you have to first be idling at or near the correct RPM to be using the idle circuit exclusively. You may have a separate vacuum leak, which can also cause the idle screws to have no effect, but your open throttle blades are a huge vacuum leak in their own right which can be reduced by closing them via the curb-idle screw.

As for vacuum, you want to measure the manifold vacuum. What you would be measuring at the vacuum advance unit on the distributor is not that. Manifold vacuum is the negative pressure being built up in the engine as the pistons are drawn downward through their intake strokes, effectively sucking air inward. This can be impacted by your idle speed and efficiency, so it is a good way to visually observe the ideal setting of your idle mixture. Like any vacuum, a seal is required to keep it from venting to the outside, so the throttle position dictates the potential for vacuum heavily. A closed throttle and relatively high RPM are the right conditions for high vacuum. This would happen at idle (though RPM are generally low), and also at cruise/coast conditions where the engine is spinning quickly, but your foot is off the gas, or mostly so. The condition of your valves can also impact vacuum potential, as well as your camshaft’s grind. For this conversation, don’t worry about that. Just understand that the vacuum in the engine’s intake manifold is what you want to measure to assess whether a leak is suspected, and to gauge your effects on idle quality through tuning efforts.

Ford designed the cars from the mid 60s to operate with a ported vacuum advance. The vacuum advance is the unit on your distributor that has the steel line running to it. Measuring vacuum here is not of much use, since it only sees vacuum when the throttle blades are opened. The “port” for the vacuum advance sits above the throttle blades in your carburetor, so when idling with the throttle blades closed, no vacuum is pulling air through that port. Imagine the analogy of sucking through a drinking straw with your finger on the bottom. Inside the straw, a negative pressure, or vacuum, is present. This would represent the intake manifold where suction is effectively being applied. Your finger would be the throttle blades. If you poked a pinhole in the side of the straw, a small amount of air would be drawn in from that spot, but nothing on the other side of your finger would feel suction. In the analogy, the small hole would be your idle air/fuel allowed to enter beneath the closed throttle blades. Now, if you remove your finger, air from the end of the straw is being pulled through unrestricted, and a negative pressure would be felt around the surrounding area. Imagine a second, smaller straw being held just beyond the end of the straw. When you move your finger, the draw of air would create a vacuum for a time in that straw as well, this would be the ported vacuum source in this scenario. All this is to say that you should not measure vacuum here, it really doesn’t tell you anything of substance.

Look instead at the rear of your intake manifold. You should see a brass fitting that supplies vacuum to your transmission’s modulator valve diaphragm. This is a good place to measure manifold vacuum. If you have one of the early steel lines going to the transmission, another spot is the PCV valve hose nipple on the carburetor spacer to the rear. A stock, or near-stock V8 should pull around 17-21” of mercury at idle. You have to close the throttle first—this may come close to stalling the engine—then smooth it out with the idle mixture screws and adjust your base timing and dwell at this lowered RPM. Adjust the idle mixture at around 500RPM while in drive, or around 600 in park. Ideally, adjust while under a load, as this is how the car will be performing when actually driving. This is more important than what it does when sitting in park, though these are closely related. Remember that idle speed affects timing and vice-versa, so you really have to adjust both of these metrics together to get it right.

 

[Woodchuck]

If it is a vaccume leak, how did you stop it?

You repair/replace the cause of the leak. Some possibilties include, but are not limited to....

1. Carburetor base gasket between carburetor mounting flange and carburetor spacer or carburetor throttle shaft(s) to main body.
2. Gasket between carburetor spacer and intake manifold flange.
3. Distributor vacuum line at carburetor (right side ahead of the throttle shaft).
4. Thermostatic choke assembly, seal between carburetor mounting ear and choke housing.
5. Ruptured distributor vacuum advance diaphragm or leaky tube fitting on vacuum line.
6. Intake manifold vacuum "tree"/fitting at rear center of manifold (V8) or under carburetor spacer (I6) or hoses connected thereto.
7. Brake vacuum assist booster hose, check valve or ruptured diaphragm.
8. Automatic transmission vacuum modulator hoses, line or ruptured diaphragm.
9. If equipped, Positive Crankcase Ventilation system hose to carburetor spacer, and/or valve at RH valve cover.
10. Intake manifold port to cylinder head port seal (intake gaskets) (V8).

 

[Bcrandell]

If you are idling at 1000 or more RPM, the idle mixture screws will have minimal to no effect on it running, because you are getting air and fuel through the transfer and main power circuits. The idle mixture screws adjust the fuel allowed to be pulled from under the closed, or mostly closed throttle blades. Air comes from the idle air bleeds that are part of the booster venturi assembly. There is not a separate air screw, but you have two idle mixture screws, one for each bore of your carburetor. The air is pre-determined by the air bleeds and whatever can be drawn through a slightly cracked open throttle plate. You are adjusting the fuel to match that air at the correct ratios. In order to do that, you have to first be idling at or near the correct RPM to be using the idle circuit exclusively. You may have a separate vacuum leak, which can also cause the idle screws to have no effect, but your open throttle blades are a huge vacuum leak in their own right which can be reduced by closing them via the curb-idle screw.

As for vacuum, you want to measure the manifold vacuum. What you would be measuring at the vacuum advance unit on the distributor is not that. Manifold vacuum is the negative pressure being built up in the engine as the pistons are drawn downward through their intake strokes, effectively sucking air inward. This can be impacted by your idle speed and efficiency, so it is a good way to visually observe the ideal setting of your idle mixture. Like any vacuum, a seal is required to keep it from venting to the outside, so the throttle position dictates the potential for vacuum heavily. A closed throttle and relatively high RPM are the right conditions for high vacuum. This would happen at idle (though RPM are generally low), and also at cruise/coast conditions where the engine is spinning quickly, but your foot is off the gas, or mostly so. The condition of your valves can also impact vacuum potential, as well as your camshaft’s grind. For this conversation, don’t worry about that. Just understand that the vacuum in the engine’s intake manifold is what you want to measure to assess whether a leak is suspected, and to gauge your effects on idle quality through tuning efforts.

Ford designed the cars from the mid 60s to operate with a ported vacuum advance. The vacuum advance is the unit on your distributor that has the steel line running to it. Measuring vacuum here is not of much use, since it only sees vacuum when the throttle blades are opened. The “port” for the vacuum advance sits above the throttle blades in your carburetor, so when idling with the throttle blades closed, no vacuum is pulling air through that port. Imagine the analogy of sucking through a drinking straw with your finger on the bottom. Inside the straw, a negative pressure, or vacuum, is present. This would represent the intake manifold where suction is effectively being applied. Your finger would be the throttle blades. If you poked a pinhole in the side of the straw, a small amount of air would be drawn in from that spot, but nothing on the other side of your finger would feel suction. In the analogy, the small hole would be your idle air/fuel allowed to enter beneath the closed throttle blades. Now, if you remove your finger, air from the end of the straw is being pulled through unrestricted, and a negative pressure would be felt around the surrounding area. Imagine a second, smaller straw being held just beyond the end of the straw. When you move your finger, the draw of air would create a vacuum for a time in that straw as well, this would be the ported vacuum source in this scenario. All this is to say that you should not measure vacuum here, it really doesn’t tell you anything of substance.

Look instead at the rear of your intake manifold. You should see a brass fitting that supplies vacuum to your transmission’s modulator valve diaphragm. This is a good place to measure manifold vacuum. If you have one of the early steel lines going to the transmission, another spot is the PCV valve hose nipple on the carburetor spacer to the rear. A stock, or near-stock V8 should pull around 17-21” of mercury at idle. You have to close the throttle first—this may come close to stalling the engine—then smooth it out with the idle mixture screws and adjust your base timing and dwell at this lowered RPM. Adjust the idle mixture at around 500RPM while in drive, or around 600 in park. Ideally, adjust while under a load, as this is how the car will be performing when actually driving. This is more important than what it does when sitting in park, though these are closely related. Remember that idle speed affects timing and vice-versa, so you really have to adjust both of these metrics together to get it right.

Ok so I got the RPMs down to where they should be and the idle screws adjusted properly. I do belive there is a vaccume leak in the intake manifold since I was the one who put that back on, I'm gonna limp the car down the road to a friend who owns his own shop and specializes with these old cars so he can make sure that everything is put together right. But it does make it so much easier to work on these things when I actually know how they work. This whole project is a learning experience for me so I really appreciate the in depth explanation. Especially since I only knew how to put a carb together and not how it works. But with the screws adjusted, the stay running while in gear instead of shutting down. It still doesn't sound the best but it should be enough to get it to the shop.