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'77 Chrysler Cordoba - "Gross Polluter"

Since a few years back, my dear 82 yr old mom (here in California) has had to take her 77 Cordoba to a smog station because the California Govt has declared her vehicle to be a gross polluter.

Never mind that she drives under 2000 miles per year and keeps the car well maintained.

So, this year a friend of the family brought the car to the smog check for her. He drove it on the freeway and got it all nice and warm before taking it in.

Bottom line: The car didn’t pass inspection. The reason: “It is running too rich”.

Of course, due to the nature of our Calfornia bureaucracy, the smog station for these gross polluter checks can’t do any repairs.

Now she’s had to make an appointment at her regular mechanic’s garage to fix it. This shop knows the car inside out and has exclusively worked on it since it was a new car.

But they’re telling her she will need to leave the car there for the whole day.

I’ve explained here that I’m not much of an auto mechanic, so that’s why I’m asking the experts here…

Wouldn’t the fix in this case be a simple carburator adjustment?

Could I do it? What tools would I need?

Leaving the car for the day is not an unreasonable request. If they know the car inside and out and you trust them, drop it off with them and let them fix it.

Yes, a carburetor adjustment (or in view of the car’s age–perhaps a carburetor overhaul) should correct the problem.

However, you should have the mechanic make sure that the car is up to date with all of its maintenance while it is there. A clogged air filter could also contribute to this problem.

Yes indeed, the fix, hopefully, will be a simple carb adjustment, much like tuning up a lawn mower, which shares the same technology as Mom’s Cordoba…

Lets see, a 318 Cu in V8, right? Remove the air cleaner (not just the lid and filter but the entire thing) from the engine. Look down near the bottom where the carb is bolted to the engine. There will be two adjustment screws facing forward, on the right and left side of the carb. These adjustment screws might have been sealed at the factory to prevent “tampering” but by now, the seals have certainly been opened so the screws should be accessible.

With the engine warmed up and idling, turn the screws in one at a time until you detect the engine slowing down a little (lean drop). Then open the screw just a little so the RPM starts to recover. Follow this procedure for both screws in turn and you Cordoba should pass just fine…

With respect, based on your level of expertise and the age and carburator technology of the car I would not recomend trying to fix this yourself. The cause of this could range from a weak ignition system to a submerged float in the float bowl. You’d need diagnostic skills to even begin.

Tweaking carburators, of for that matter attempting any repair, without first being able to diagnos the root cause(s) of the problem is more likely to make things worse than to repair it.

Thank you, Caddyman, for your explanation. I suspect you’re correct and that your instructions will work. However, given the other great advice written by others, I think I’ll leave it to the shop to make the adjustment.

Although I think I could pull this one off, I’d probably just make things worse if the reason turned out to be something other than the carburator.

Just adjusting the idle mixture may not fix the problem,you must find out what caused the car to need it’s mixture adjusted,the car we are speaking about in in an era of poor emission control devices,again not all “gross polluters” are fixed by a carb adjustment.

I am susprised that the shop you praise so much did not notice the car was running so poor,a experienced mechanic can spot a gross polluter just by seeing,listening and smelling.

The only adjustment on the carburtor is the idle mixture screw and this affects the mixture setting at idle only. Off-idle it’s irrelevant.

On many carbs of this era the mixture screws are pinned to prevent tampering. To adjust them often requires removal of the carb or some serious digging to get the anti-tamper pins out.

If the problem is running excessively rich at elevated RPMs then the idle mixture is not the problem. If this car is equipped with Lean Burn then it’s possible there could be an ignition timing problem. Timing that is retarded too much will cause a rich running condition.

“I am susprised that the shop you praise so much did not notice the car was running so poor,a experienced mechanic can spot a gross polluter just by seeing,listening and smelling.”

Actually, the car is not running poorly. I drove it yesterday and it runs great.

Also, this car is designated as a “Gross Polluter”, not based on its own performance, but because the powers that be in California have determined that it has “a high probability of failing the Smog Check inspection”. This is the first time it has failed. I believe this is the third time it has been required to be tested at a ‘Test Only’ station.

If the car is running OK, then it is unlikely it has any of the other problems mentioned. I suspect this car must pass at idle only, there is no requirement for a “high speed test” or “load test” right?? If it’s an idle only test, then a simple carb adjustment will make it pass. If it will “lean drop” as I described, then it can be adjusted to pass the CO portion of the test…If you can screw those mixture screws in tight and nothing happens, the engine continues to run without the RPM dropping, then the carb is leaking internally and will need to be rebuilt.

Caddyman, I believe the smog test does include a high speed test - if that is what is meant when they put it on the machine and do simulated high speed driving with the car’s wheels actually spinning.

But I don’t know if there’s any difference in a smog test if they are saying it’s “running rich” at a high speed as opposed to at idle. The solution would be the same… no?

Again, I’m guessing that your simple solution is going to be the ultimate fix and I’ll post the result here when I find out. I think she’s taking it to the shop next week and possibly back to the smog station later in the day or week.

The carburetor in the 318/360 engines had a design flaw in them around the 1976/1977 years. When you tightened down on the air cleaner (via that wing nut), the threaded shaft would “lift up” on the upper half of the carburetor - causing it to warp and not seal properly to the lower half (the bowl half). Once that gap began to break open, it would cause an overrich condition, sometimes accompanied with driveability issues.

The “dealer fix” from Chrysler for that problem was to “sand it flat” again.
This involved getting a sheet of wet sandpaper, placing it on a flat surface (like a heavy piece of glass), removing the top half of the carburetor, and then sanding/swirling the carb top over the sandpaper until you could see the surface was flat again. It was easy to see when the whole mating surface was shiny and clean (as opposed to aged and pitted). Then wash it off and replace the top on the carb.

I did hundreds of these carb “fixes” when I worked in a dealer then. We had to even reuse the gasket between the top and bottom halves because the warranty wouldn’t pay for it. Chrysler did eventually fix the design, but not until many many of these carbs already shipped on new cars.

Of course, if the air cleaner wing nut was overtightened again, the warpage would start all over again.

With such low mileage, put in fresh spark plugs for the emissions test. Also, it might help to put in fresh distributor cap and rotor. You don’t have to throw the old parts away. All engines misfire without it being noticeable. Of course, if the misfire gets bad enough, you will notice. Each misfire sends a cylinder-full of unburned fuel out the exhaust.
The shop should be using an exhaust gas analyser when they make adjustments / repairs.

Subarus also had a problem with warped carburetor sections which would in turn cause air leaks and internal fuel leaks.
Most used the Hitachi carbs and this was a very common fault with them although it was not caused by tighening of the air cleaner screw. In this case it was heat warpage.

Have filed many of them flat although the problem would often surface again in a few years.

California is in its own little world when it comes to emissions…And not just car emissions… If they put Mom’s Cordoba on the rollers, then it was also tested at “road speed”. Your test report should detail exactly when the failure occurred, at idle or at the higher speed. Adjusting the idle mixture will have little effect on the “road speed” portion of the test…

During this era, Chrysler used something called “lean-burn technology” which theoretically would produce very low CO readings. Getting one of these cars to meet California standards today could be very difficult. Look into a “loop-hole” you can squeeze through. How about registering the car as a “Classic”? In many states, that ploy will exempt you from emissions testing.

I would avoid buying a high-dollar “rebuilt” carb unless it came with a guarantee the car will pass emissions.

If you could scan, then cut and paste the test report to this board, we could offer better help…

High CO has NOTHING to do with mis-fire…This is a rich mixture problem. Misfire causes high HC, hydrocarbons, unburned fuel…A better approach would be to attack the PVC system, clean it all out so more air volume can flow through it…This will lower CO…

A misadjusted choke or an old choke thermostat will cause a problem like that. It isn’t always a simple thing to find the reason. It could be a fried wire that usually heats the choke thermostat. It may not be running too rich; the catalytic converter may have reached the end of the line. Plug wires, plugs, vacuum lines, and ported vacuum valves can all stop working. There are at least a dozen possibilities.

The OP said that it’s, “…running too rich…”, and failed the emissions test. Rich isn’t HC?

Joe Guy,
Do you have the exact emissions test readings from the test sheet? If so, let us have them, so that we’ll know if you are talking about CO, or HC, or whatever.

I’ll have to talk to my dear old Mom.

Hopefully, I can call and get the info by tomorrow to post here.

thanks to all for your thoughts and ideas.