Stalling on warmup?

[ArtemisI6]

Hello all,

As you can see I'm new to this forum. I'm very happy I stumbled upon this as I'm a huge fan of Ford sixes. I have had great experiences with the one in my 368,000 mile truck that I continue to use with minimal maintenance, and some day I'd like to build a new one for it. I find the idle of a hot straight six a lot more pleasing than the all-too-familiar idle of a V8, and a powerful I6 is a lot more unique than another small block V8. I find everything about these motors interesting.

Anyways, the reason I'm posting is I could really use some help. My girlfriend recently bought a 1967 Mustang that's a bit of a rusted-out beater, and I'm trying to get it road-ready for her. I've done a whole lot of work on it and we're coming to a point where it's almost driveable. I only need to replace the exhaust, change out the oil in the differential, flush any gunk out of the motor, and fix this idling issue (which I'm assuming has to do with the carburetor), and the car will be driveable for her. Unfortunately I'm a bodyman first and a mechanic second, and I've never dealt with a carburetor in great extent. I rebuilt the one on my motorcycle, and I've taken apart and adjusted the one on my truck and on this car, but I can't seem to grasp how to adjust it correctly despite having read how several times. I just can't get the car running how everyone is saying it should when I do what they tell me to.

Now, I'm assuming I screwed (pun unintended) up something while messing with the idle speeds and mixture. The car will start up reasonably easily even in the low-teens temperature we're experiencing, and it'll idle pretty good, but then when the engine starts to warm up it'll stall out. I can keep it running a little longer by massaging the gas pedal a little bit, but eventually it'll die. My father says he can smell that it's running rich, but I don't know.

I've put a Pertronix II into this and I have 12v getting to the coil. This car is extremely beat and with 88,000 original miles on it, it could definitely use a rebuilt engine, but while compression is a little low, it's even throughout all cylinders and I have in the past gotten the car to run impressively smoothly, and I have taken it for a drive several times. However it's a crapshoot as I don't have enough experience with carbs to be able to read what the engine's doing and know how to remedy it.

The carb was recently rebuilt by her father, but he seems to break things more often than fix them and I have found myself several times fixing his mistakes on both this car and her mother's car. Regardless of that, I believe this time he didn't mess anything up with the carburetor as I had the car running smoothly some time ago. I believe this was caused by my messing around with the adjustments trying to fix another issue I was having with the car.


Anyways, I'd REALLY appreciate it if someone (or several of you, the more input the better!) could assist me in fixing this problem. Thank you!


EDIT: It is an Autolite 1100, by the way.

 

[fordconvert]

Do you know which carb is on it?

I would only use the word rebuilt if you sent it to someone like pony, the rest of the time its cleaned up and threw in a kit. Common issues I have seen with the 1100 seem to be cracked exhaust manifold letting exhaust into the choke and from there things get messy. On mine I had to drill out some passages because there was so much carbon in places.

This is an 1100.

 

[ArtemisI6]

I forgot to mention it's an Autolite 1100.

 

[fordconvert]

When you installed the pertronix did you reset the timing? Does the vacuum advance in the distributor work? Where is it connected to and are there any devices in that line? Does the mechanical advance work? Does the choke appear to be working? Does the fast idle seem to be workin? Whats wrong with the exhaust? Once its warmed up it does seem to run fine?

 

[Asa]

your dad says he can smell it's running rich, how do the plugs look?

 

[69.5Mav]

Sounds to me like your choke may not be opening as the car warms up.

Look down the carb to see if it is.

 

[ludwig]

In your case, the choke pull-off would be adjusted with the nylon nut between the black cap and the carb throat, as shown above.

If you don't have a dwell tach, you can adjust the timing with a vacuum gauge. Hook the VG up to a manifold port on the log.

With the car fully warmed up at idle, block the four wheels, put it in D. Then turn the distributor counter clockwise until the the vacuum peaks. It should be at 18# or more. You will have to back the standing idle off from stock if you have installed DS or PTRX or some other electronic ignition. 700 to 800 RPM is your target.

Now adjust the idle air/fuel mix. I forgot where this screw is, but it is down below the choke/throttle stuff. (I think it is near the base of the carb throat toward the front, next to the bowl. Turn it in until the engine starts to stumble and back it off to where there is peak vacuum. Now give it a quarter turn more.

Now you start fooling with the choke. The frustrating thing with this is that you can only do it with the engine cold. Once it is hot, you have to wait for it to cool off again, so you only get one good shot per day unless you live where it is cold.

If all the other stuff is good and you are getting 18# of vacuum or more, then fool with the nylon nut to slow down or speed up the choke pull off. In your case, it needs to go slower.

If you get a dwell tach (it doesn't have to be expensive; $30 or so) you get the idle and timing in spec and then start with the choke stuff. If you flat out can't get it to idle, fool with the white nylon nut first to adjust the limits of the choke pull off.

If it is running rich (gas smell), adjust the idle fuel mix to lean it out. You absolutely WILL have to lean out the A/F mix and set the idle back when you got to electronic ignition.

 

[ArtemisI6]

Sounds to me like your choke may not be opening as the car warms up.

Look down the carb to see if it is.

The choke is opening. The car runs fine with it closed, then as it gets midway open the idle actually smooths out a bit. Then when it gets closer to fully open the car starts to stumble and then dies.

When you installed the pertronix did you reset the timing? Does the vacuum advance in the distributor work? Where is it connected to and are there any devices in that line? Does the mechanical advance work? Does the choke appear to be working? Does the fast idle seem to be workin? Whats wrong with the exhaust? Once its warmed up it does seem to run fine?

Yes I reset the timing according to factory specs. However I may end up redoing it with a vacuum gauge.

I don't know how to check and see if the vacuum advance works.
I also don't know how to check and see if mechanical works.
The choke works fine.
Fast idle seems to be working to me, but I can't be sure.
The muffler is all rusted out and needs to be replaced.
I can't get it to warm up because as it warms up it dies.

I have not checked the plugs lately but I will do that now.

I just did some tinkering and realized that the accelerator pump does not appear to be working. When looking down the carb with the chcke open and moving the throttle linkage to mimic flooring the pedal, nothing squirts out whatsoever.

Also, I just got it running and was messing with the mixture screw, and it appears that it's not having any effect on the car whatsoever. Whether I turn it all the way in or out, the car does not change in idle at all. Of course this is still under fast idle when the car is warming up, so I don't know enough about this stuff to know if it should affect it then, but it seems to me that it should.

Thank you for all the suggestions so far.


EDIT: I was in the midst of posting this while you posted yours ludwig; can you tell me what the "log" is? I have a DMM with a inductive pickup that I can use as a tach also, but I'd like to do it with vacuum as this motor is so worn out I doubt the factory specs will do the best at this point.

 

[ludwig]

If you have determined that all the idle/fuel mix/vacuum stuff is in order, you have to make sure the choke is actually coming off.

Unscrew the black cap and see if the bimetal coil spring is intact. It may be 1) broken or 2) have come disengaged from the pull off tang at the carb side. If the inside of the cap is full of soot, it means that the wall in the manifold where the pull off air is heated has rusted through and now hot exhaust is being sucked into the cap. This requires an aftermarket stove and pipe to get clean air into the spring cap.

If the cap is relatively clean, the pull off mechanism itself is hanging up somewhere. Clean the mechanism fully inside and out with carb cleaner and small brushes. Work it back and forth manually by hand (finger) and observe the choke butterfly running easily. DO NOT use any lubricant. This will turn gummy and block the free movement. If there are any spots of rust on any of the slides or shafts, buff them out with fine grain paper.

There is a little pointer bump on the outside rim of the cap. It should be at the TOP. Reassemble the tang/spring/cap setup (this will take a couple of passes to do right) and fasten the cap with the ring and three screws LOOSELY. Run the cap back and forth to make sure the choke plate opens and closes with minimal effort. Note where the mark is lands when it just starts to pull off. Then turn the cap counter-clockwise until the choke just closes. If your engine is hot, set it at the open position. If it is cold, set it at the closed position.

Now fire up the car and see if it opens and closes properly.

 

[fordconvert]

The Log is what we call the intake manifold which is cast right into the side of the head and sort of looks like a log.

If the idle mixture screw does nothing something is not right. Lots of possible causes. I would say its time to pull the carb. Could be something is plugged up. Could be it was put together wrong last time. There are check balls and a weight involved in the accelerator pump. With this design if the diaphragm is bad it will tend to leak externally so its likely a problem inside.

 

[ludwig]

If the idle mixture screw does nothing something is not right. Lots of possible causes. I would say its time to pull the carb. Could be something is plugged up. Could be it was put together wrong last time. There are check balls and a weight involved in the accelerator pump. With this design if the diaphragm is bad it will tend to leak externally so its likely Ia problem inside.

Ditto. Sounds like the transition tube from idle to run is plugged up. Rebuild the carb with a good quality kit (cheap, really) and blow out and clean all the passages and shaft races. Use a can of computer cleaner compressed air to blow out the passages in the carb throat after you squirt carb claner into them.

Your big goal is 18 pounds of vac at a minimum. As you improve the machine, the specs will change from factory. Don't worry. Here and there you will end up resetting them, so just remember the new numbers where it runs well.

 

[ArtemisI6]

After some more tinkering just now I've gotten the accelerator pump functioning at least partially. It still stumbles when I rev it but not to the point that it wants to die.

I took apart that automatic choke cap and the spring was intact. There was also no soot inside there. It wasn't clean by any means but there was nothing built up in there. The choke is opening, but the problem is that just as the car begins to warm up it and I can see the choke beginning to open, it begins to quickly sputter and die. If I open it with my finger while the motor is still cold, it does not start to sputter until it's past midway open. This seems to me like that means it's not a choke issue.

I'm going to probably have to take this apart and rebuild it again, huh? As far as I know the only cleaning her father did was soak the entire disassembled carb body in gasoline for a couple days, then reassemble it with new parts.

 

[ludwig]

Well, there is part of the problem. Use carb cleaner, not gas. Modern gas has compounds in it that turn to gum when they dry out. If it just sat in a bowl of gas, it loosened the offending particles and allowed them to drift into a new position.

If you did nothing with the A/F mix after putting on the electronics, that is part of your problem. Incomplete combustion is a problem for points ignitions. You require less fuel with electronics, so you can lean it out considerably. If nothing changes when you turn the mix screw something is definitely wrong and will require a real look-see.

Apparently it is running rich and you are having a problem in the transition cycle. You may also be having a needle valve problem and too much gas is forcing its way into the carb. Check the needle valve itself. The tip is often a hard rubber point and these will be eaten away with gas containing ethanol.

There may be contamination of the brass seat and this is holding the needle off of the fully closed position. Also, you need to make sure the float is set at the right level and this is done with the carb held upside down using a little cardboard gauge in the rebuild kit.

 

[NC-Fordguy]

I experienced something similiar with a 66 Bronco I bought a few months ago.

Truck would run fine with choke pulled or shifting into low range.

After much agravation, posting in this forum, use of every colorful phrase I know, consulting tech manuals, etc, turned out the problem was in the accelerator pump housing. I guess over the years it had been over tighten and developed a "cup" to it, rather than laying flat. The result was a small squirt of gas leaking from it. It was nearly impossible to see as it would vaporize almost instantly when hitting the intake.

I ended up snagging a couple of 1100 on fleabay and took the best parts of 3 carbs and built one that worked

 

[jahearne]

I just experienced a similar problem with my 1100. I have a '67 with non-SCV dizzy. For the time being I swapped carbs from a non-SCV 1100 to a SCV carb and moved the vacuum advance from port vacuum to manifold vacuum.

After I rebuilt my carb, I left the dizzy vacuum hooked up to manifold vacuum. Once I replaced the dizzy vacuum back to port vacuum off the carburetor, it ran fine and the stumble went away.

How the Spark Control Valve (SCV) Works
http://fordsix.com/forum/viewtopic.php?t=18841

Pre-68 Load-O-Matic - How it operates
http://fordsix.com/forum/viewtopic.php?t=15522

Good luck,

 

[CobraSix]

I agree, sounds like the transition or normal circuit is clogged up. Sometimes it can be completely random. I remember driving home from work one day, car ran fine. By the time I got how, I could only keep it running as long as I kept my foot on the pedal and kept the RPM above 2k. Pull off the carb, rebuilt it, put it back on...ran like a champ again.

 

[ArtemisI6]

Sorry guys, I haven't been replying as I've been a bit busy. I pulled the carb apart to find the entire thing varnished to hell and back, with a nice layer of loose sediment covering the bottom of the float bowl. I was also missing one of the check balls, and the tip of the mixture screw is bent very slightly. I got a new check ball but haven't yet located a new mixture screw. While I didn't soak it (my local autoparts place didn't have any of the carb clean a bottle, only in a spraycan), I sprayed it and wiped it out really good and ran compressed air through every passage I could find. Not being quite fully familiar with carbs yet, I don't know what circuit is what, but I made darn sure at the very least that the passage that the mixture screw blocks off was completely clear as much as I could.

However, now with a new check ball and a cleaned out carb, the car is still running very roughly. I'm not sure if it stalls when it warms up yet as I didn't have a chance to wait that long, but I did notice that the mixture screw still does not appear to affect the idle quality of the car whatsoever.

It would also appear that my solenoid has decided to take a dump, so I will have to procure one of those possibly tomorrow.

 

[ArtemisI6]

Hey guys, sorry for the lack of updates. Been too busy. I ended up at least partially fixing the stalling on warmup. I took a close look at it and realized it was stalling as soon as the choke came off the fast idle cam. I turned the idle speed up a little bit more, and turned the black-cylinder choke spring thing (its name always escapes me, LOL) more towards lean and it's now able to continue running. We registered it Thursday night too, and I drove it all around town!

However, I can't freaking adjust anything properly because it has a nasty misfire somewhere. I can't track the darn issue down because no matter what spark plug I pull, the idle stays the same - very rough. The plugs have a very satisfyingly light brown color, so I believe at the moment its mixture is pretty ok.

It has (as far as I know) the stock coil, brand Motorcraft wires, brand new Autolite spark plugs, a brand new cap/rotor, and the Pertronix Ignitor II module. I did not remove the resistance wire because I was getting 12v at the coil with the ignition on. I can't explain why that is (that fat pink wire was still there), but this car has been completely hacked apart and ruined by some moron in the past. I'm been fighting an uphill battle fixing their mistakes and I'm not really worrying as to why I have an unexplained 12v at the coil since that's what I need anyway.

My wonder is if this misfire is caused by an ancient coil, or by the Ignitor II? I know how most of you guys feel about Pertronix but my girlfriend (this is her car) spent $110 on the darn thing way before we heard the horror stories about the six-cylinder modules. She's in college at the moment so she can't really afford to go to any other, more desireable electronic ignition swap at the moment - so I'm hoping there's a way I can make due with this.

The car is stalling intermittently when getting off the gas to come to a stop. I'm thinking the misfire is heavily contributing to this and either way it's impossible to make any adjustments with this going on.


Do any of you gurus have any suggestions? I'd really appreciate it.

 

[ArtemisI6]

Hello! Just another update -

The stalling was being caused by a pinhole leak in my fuel line, and the miss was remedied by a new chrome-plated coil from Summit.

Thanks guys!