1986 Corolla LE Failed Emissions

I have a 1986 Toyota Corolla LE and I need some help. It won't pass smog. Here are the failures.

HC (PPM): 130 @ 15MPH
151 @ 25MPH

CO (%): 0.84 @ 15MPH
2.86 @ 25MPH

The 25MPH readings are what failed. Any suggestions?

I understand this means it's running rich while at speed. How can I adjust the mixture of the carb so it will pass?

Some info:

http://www.type2.com/library/exhaust/comix.htm

I would check to make sure that your O2 sensor feedback system is working properly, and that the engine is sufficiently warmed up -- a cold engine (with respect to the ECT sensor) will run rich with advanced timing (the old carb "choke" function) -- You do not have a carb that you can adjust (EFI uses a throtle body), it's all done by the PCM controlling fuel dilivery with the injectors with input from the sensors, all of which need to be functioning or the box will be effectively "blind."

Changing the oil may help if it has broken down, or is too thin (light weight, ie OW or 5W) and your cylinder bores are worn, or the engine is otherwise burning oil -- some injector cleaner in the fuel will help lubricate the injectors and possibly correct one that's stuck open a bit, causing the rich condition. Check the static ignition timing -- over-advanced initial timing will increase CO.

oops: I was "thinking" 96 ! -- you may need to replace the carb if it is running too rich, but first make sure that the choke blade (if it has one) is fully opening and that there is a clean air filter and unobstructed path to the air filter element. The ignition timing should also be checked, and any vacuum or mechanical advance stuff that may be in your distributor.

It's also possible that the timing belt/chain(?) that spins the cam(s) may be stretched, causing inaccurate valve and ignition timing.