Catalytic Converter Maintenance?

[ed1948]

Re: my recently bought 86 all stock Monte Carlo SS with 90 miles.
Would there be any benefit for re and re'ing the cat to check for possible carbon clogging? I want to keep the cat in the system. I'm owner #5 and have no idea how the car was driven in the past. It runs well with almost smoke free start ups, plugs are clean and acceleration seems ok. I assume hard, agressive driving would lead to self cleaning of the cat? I have no issues with checking and cleaning the cat if needed - is it a time waster to do such a thing? I think it would be more fun to do an Italian tune up.

A friend(with G Body experience a few decades ago) tested the car and felt the top end power should be a bit stronger. He thought the carb might need adjusting. He didn't say anything about the cat.

 

[L67ss]

Just run gas and keep the engine well tuned. Won't be a lot of top end with a 305

 

[Jeff L]

If the car is running ok just keep up with the maintenance and you should be ok like L67ss said.

Some signs the convertor is clogged is loss of power and the engine might start overheating because the exhaust is being partially blocked. Some swear you can take off a convertor and clean the insides with soap and water or some kind of solvents. Not sure about that...? I do know once it is clogged it needs to be replaced.

I have 109,000 miles on mine and it is ok. Never had an issue with the exhaust.

 

[L67ss]

Yeah seems like cleaning it would put it at risk of the insides breaking up....especially if you don't get it completely dry. A new 50 state legal cat will run about $100

 

[pontiacgp]

you can check the converter, just let the engine get to operating temperature and with a laser temperature gun check the temperature of the front pipe of the converter then the rear pipe of the converter. The rear pipe should be less than 150° hotter than the front

 

[motorheadmike]

Italian tune up? LMFAO! Never heard that one before.

But, if it is clogged jam a broomstick through it, and replace it once you get tired of the smell.

 

[ed1948]

Italian tune up? LMFAO! Never heard that one before..

Drive at near max rpm for a while AKA Italian Tune Up

 

[Ve8r]

If you suspect a cat is clogged you can remove the 02 sensor to test if there is a restriction. ( leave the 02 connected), just remove it from the exhaust. Tie it up so it does not drag or get caught on anything , and test drive. Mind you it must be a upstream 02 sensor or before the cat if you will. Yours should only have a upstream ( modern cars have a downstream as well).
If power is noticeably better it's a good possibility the cat needs replacing.
Remember a clogged converter and fuel starvation have similar symptoms. Make sure your fuel system is in good working order.

You say your buddy says it feels down on top end power, are the secondaries opening up on the carb at WOT?

 

[ed1948]

Ve8r - Checking the carb is on my to-do list once everything on the car is re-assembled.

 

[Ve8r]

Ve8r - Checking the carb is on my to-do list once everything on the car is re-assembled.

Make sure the cam on the secondary air valves is intact and the tension on the air valve spring isn't too tight. Too loose and you will get a bog, but too tight isn't good either.
Next time your at the bone yard look and see if they have a pile of Qjets laying around. If so snag a few different sets of metering rods and hangers. They are great for tuning