Carberator issues

I've had the Cougar (200 six with Motorcraft 1 bbl carb) for 7 years now. For all 7 years I've had many issues with carbs and corrected all but one issue. It won't go away.

The carb will boil over after shutting down the engine after operating a full temperature. This results in hard starting when warm after about 20 minutes. The problem with starting does not happen after the engine cools down for an hour or so.

What I've tried:
1. Lowered the float
2. Lowered the float some more
The float is now 3/16" (0.5 mm) below spec.
3. Changed timing to 8* BTDC
4. Changed timing to 12* BTDC
5. Installed heat shield between carb and manifold.
6. Tried double gasketing of the carb to manifold mounting.
7. Tried running the car without a aircleaner to test.

Now the configuration is the float is at #2. The heat shield is removed. The timing is at 8* BTDC. The engine does not overheat. I believe the thermostat is a 190* per spec for the 82. Everything on the car is stock and all emissions controls are present and functional.

Certainly this condition would never have been tolerated for a new car. The car runs up to 80 mph easily. The around town gas milage is always 17-18 mpg. What the heck is causing the excess heat? To me the underhood temps are quite normal feeling but there has to be a large heat transfer to the carb.:confused::confused::confused:

 

I wonder if it's related to the exhaust system. If there is excessive backpressure the system, including that ungodly thing hanging off your exhaust manifold, will get too hot, and then when the engine goes off the heat could soak up to the intake manifold just like sitting on a stove element. Maybe take a few temp gun readings around there after going for a drive and see how hot it gets.

You know my engine started getting it's rebuild when I discovered hairline cracks all through the manifold, and it's just the regular one. I'm surprised yours isn't showing any signs of failure, but then how much do you drive it?

 

I probably put a couple of thousand miles a year now on it. I thought of exhaust too but thought that any restriction would also restrict performance. Kind of an oxymoron...performance. I have the 2.73:1 rear end. I could remove the cat again and take a look at that. I could have melted it somewhat when it was running lean, really lean in 08. It did drive very nice when I went down to the Fabulous Fords Show but it did act like it was flooding in the stop and go traffic to the point it would almost stall. I think exhaust is the only thing left in the equation.

 

The only problem with the restricted theory is that the vacuum gage doesn't indicate a problem with exhaust.


I AM TOTALLY BEFUDDLED ON THIS PROBLEM!

 

Are you harbouring a politician under the hood?

I can't get mine to move the gauge from N to O in Normal, and you've got too much of it. Hmmm.

Do you have that 'anti-dieselling' solenoid too? Andy takes them off and our cars run fine, summer or winter.

 

The primary purpose of that solenoid on mine is to kick up the throttle when turning on the a/c. It's not being used at this time.

As far as engine temp is concerned it's normal. Not high at all but the exhaust manifold must be getting pretty hot to cook the fuel. It doesn't result in flooding while driving at all. Air cooled during driving but the residual heat apparently is cooking the fuel after shutdown.

As you know engines just wouldn't run right if the manifold is cold all the time. Thus is why most inline engines have the intake above the exhaust manifold. Heat makes fuel atomize properly. Crossflow inline heads usually have some method of heating the intake manifold, usually with water. V engine manifolds are almost always heated with water or if not exhaust is routed through them.

 

Do you have a clutchfan or an electric fan? An electric fan would do the trick, since they run until the sensor says its 'cool', even after the key is off. I wonder if you could just get the fan circuit and hookup a small fan toward the carb/manifold? Set the upper/lower range and you're done! It would shut off when you're driving, and after that area was down to the normal engine surface temps.

 

Norm, I understand what you are saying and the F-150 had a fan that would blow across the manifold but, there must be a reason, whether the exhaust or whatever is causing the problem. Corrective action must be possible without modification or altering the car beyond the original design. Sure I could install a fan or heat shield or someother method but the car was not designed that way and certainly wouldn't have been acceptable from new the way it is.

There just has to be a valid fix within the design to begin with.:banghead3:

 

Does the hard starting problem occur only during warm weather days or all the time regardless of the outside temperature? Since you live in CA, I'm not sure what your climate is like. I have a '58 Dodge that has a hard start problem almost exactly like yours, which only occurs in the summer. The problem is vapor lock and it goes away once the fall weather arrives. My understanding is that with 10% ethanol now added to gas, vapor lock occurs at a lower temp than with pure gasoline. The answer to the hard start problem is to reroute the fuel line, insulate the fuel line and if needed, add an electric fuel pump and turn it on when the hard start pops-up.

 

No, it happens all the time. The carb is definately boiling over at about 20 minutes after running a full temp. I've never had a vapor lock problem. It's a flooded condition and only occurs after engine shut down after at full operating temperature. The condition causes a flooded condition up to an hour. After that apparently the fuel evaporates from the manifold and it starts normally. If after driving I have to start again in 10 or so minutes it starts right up with no problem.

May be you are right and there's simply not a fix with todays fuel. It did the same when we had MBTE in the fuel instead of ethynol.

Maybe I'll have to install a fan. A heat shield had no effect nor has lowering the float or changing the timing.

AAARRRGGG!

 

You know how Cougars are, they always do something to get our attention.

Have you had your manifolds off? If they were caked with soot inside, that would preserve the heat too. I'm really reaching with that idea, but since you've tweaked the fuel mixture and fuel chemistry has mixed up since 1982, that could be a factor.

 

Like you said, the problem occurs after you've shut the engine down, so what good is a vacuum guage at that point? Get a temp gun.

 

It was clear when I had the head off. But, I never checked the bottom end. I haven't had the cat off for a couple of years either. It just doesn't behave like a restricted exhaust or show on the vacuum gage like a restricted exhaust. But, it's not off my radar. One weekend I'll pull the cat off and visually check it. If the exhaust has any kind of restriction it's minor but minor could certainly affect it I'm sure. I don't have a glowing red exhaust manifold....I've actually looked. Something's amiss. Or it's something I'll have to accept.

 

Actually there is a procedure to check for restricted exhaust for the vacuum gage.

So, what will the temp gun do for me? Do you know what the exhaust manifold temperature is supposed to be? That would be good information to have when using the temp gun. Right?

 

The anti dieseling solenoidieselingd acts to allow the throttle plate to totally close when you shut the engine down, which stops the air flow to the engine. This eliminates the engine vacuum from sucking the gas from the carburetor, causing the dieseling effect.

The solenoid that kicks up the engine speed when you engage the air conditioning, is different from the anti dieseling solenoid. It is electrically operated, and it pushes on the accelerator pedal linkage, causing the throttle plate to open more, causing a higher vacuum, which in turn caused additional gas flow through the idle jets.

Unfortunately, when people don't understand how carburetors and the associated accoutrement's to the carburetor work, they make adjustments that are actually detrimental to the proper operation. When setting a carburetor, use the factory service manual, and follow each stem exactly as it says to do it in the manual. If you skip a step, you will not get the next step done correctly.