question on exhaust?


New Member
I know many of you guys are working on your GN's over the winter. I am looking for someone who has his exhaust system apart. The 84-85 hot air cars have a "all most square" exhaust flange on the catalytic converter where it meets the turbo down pipe. I need some information on the size of the flange, distance between bolt hole centers. I want to make a flange on my milling machine and make a catalytic converter eliminator pipe. I have my car in storage right now and can't get to it. Thanks in advance Mr. Buick
ok i looked at mine just cause i took the motor out yesterday and had the stock downpipe on the work bench. It is difficult to explain without a picture but here goes. Top holes center to center are 2.675 inches apart; I measured the right holes center to center 2.450 inches; and the downpipe is 2 inch pipe but the flange hole were the gasket mounts is 2.30inches across. again I measured the downpipe square flange that bolts directly to the cat. Oh and the measurements were taken looking at the flange side, from the cats "point of view"

If you need me to explain it better or anything else let me know, should have it apart untill wednesday next week.
Exhaust flange

Thank you for the measurements, now I just have two more questions. What is the total length of the catalytic converter from flange to flange. What is the thickness of the metal on the flange.