OK, here is the story. I bought an 1985 RX-7 GS with a 12A a few months ago and I am preparing it to autocross in the stock class.



The car has three catalytic converters, two precats (nearest the engine) and a main cat. I opened up the exhaust because I suspected that it was clogged. The first precat inlet looks like the picture.



I live in Houston, TX with some pretty tight smog regulations so I am not anxious to drill the precat or replace the precats with a header as this would void my stock status. It looks as though the honeycomb has melted only right at the inlet.



My question is this: does anyone think that I can take off enough of the clogged portion and leave the rest intact without it cracking into pieces? Any other suggestions other than buying a new one ($800)?





EDIT: pic WAY to big! https://www.nopistons.com/forums/pub...IR#>/blink.png

wow... my first close up of a cat... ummm I would say ditch-the-bitch... but if it runs good and you think you have a chance... go for it... as to get back to your original question... ? you are gonna get some heat and then some... good luck

Well, here it is after a successful operation. The blockage was removed by a very long 1/2" drill bit. I just ground away the melted top portion of the catalyst.

its good you saved the cat! it will pass on just a healthy main one btw



mike

Well, here it is after the successful operation. Used a very long 1/2" drill bit to take the top portion of the catalyst off.



BTW - thanks for editing the first picture. I hope this one is a little better.

what a wonderful idea you had.. looks great!

If you have a working Air tube you can get a Catco from summit for like 79 bucks I put on of these on when I switch to a Racing beat header, and what a difference. I added a catco (u could see through this thing) and it had the air tube so I could hook up my air pump to help the cat process the exhaust. New o2 sensor and I cruized through smog with 1 cat.