DIY catalyic converters?

[78TownLandau]

Was wondering how many of you upgraded or replaced your own exhaust system. I'm in the process of replacing the one on my '78 Town Landau and this is my first time messing around with exhaust pipes. Two questions:

1.) If you replaced the catalytic converters, what did you do or where did your order the cat from? The portion of the exhaust between the exhaust manifold and the beginning of the Y-pipe seems to be custom made with some non-standard bends. Universal cats are plentiful and cheap, but how do you make the connection between the exhaust manifold and the Y-pipe?

2.) How does one make a flange on an exhaust pipe?

Much appreciated,

Po

[bigbrownbird]

hey Po,
flanges are usually made with an exhaust machine. some parts stores have some hand flange tools, and while they do the job, they aren't quite as professional as a pro job. as for cats, mine were missing before I got the car :wink .

Lee

[Charles]

What I do is take the cats off, put them in a vise, and beat the substrate out of them with a steel rod and a hammer. It isn't easy to do this and it is of course illegal. Performance and fuel economy gains are significant. Wait until you are real angry with someone to do this. Makes the job much easier.

[78TownLandau]

Thanks for the info about flanges. I had suspected that it took some heat and special equipment to make the tubing flare out. I'll keep my 25-year-old cats for now, just to keep the exhaust system connected. I've scoured the internet and no one seems to make direct-fit cats for '78 cars. :nonod

I'm keeping everything street legal since I'm not sure which state I'll end up settling down in and hence which set of smog rules I have to follow. Ideally what I'd like to have is a pair of cats which have provisions for O2 sensors. This way, I can hook them up to air/fuel sensors in the cabin to monitor how the carb and engine are doing. Maybe I'll buy a pair of universal-fit cats and bring 'em into an exhaust shop and they can make the custom bends for me.

Po