'75 Catalytic Convertor

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Oct 8, 2005 | 05:41 PM

HDFLH67

Thread Starter

Racer

Joined: Jan 2003

Posts: 294

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From: Rochester NY

'75 Catalytic Convertor

Here in New York, I have to have a catalytic convertor, since the 1975 originally came with one. BUT, it doesn't have to work since I am exempt from smog testing. (yes, that only makes sense to the politicians)

Any recommendations on the least restrictive cat out there at a reasonable price? Has anyone ever opened one up to gut it, and then welded back together?

Any other ideas appreciated! Thanks!

Oct 8, 2005 | 06:01 PM

KenSny

Melting Slicks

Joined: Apr 2001

Posts: 3,399

Likes: 278

From: Olmsted Falls, Ohio

I'd get a cheapo and gut it by running a straight pipe thru it - No restriction.....

Oct 8, 2005 | 06:59 PM

Mike Mercury

Team Owner

Joined: Apr 2001

Posts: 54,204

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From: S.W. Ohio. . . . . . NRA Life Member

Quote:

Originally Posted by HDFLH67

Has anyone ever opened one up to gut it, and then welded back together?

Any other ideas appreciated! Thanks!

on my past 1975 (though Paul Borowski claims they didn't make any 1975 Corvettes...

), I simply replaced the cat with one of those "test pipes" My state wasn't doing any testing/inspection back then.

If this helps any, I gutted the "pre-cats" on my 2002:
http://mikemercury.home.att.net/precats.htm

this way - it still passes the visual inspection.

Oct 8, 2005 | 08:11 PM

Pete76Shark

Racer

Joined: Jan 2003

Posts: 383

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From: Columbia SC

Quote:

Originally Posted by HDFLH67

Before I moved to SC I lived in NJ and had the same situation you have.
I removed my stock cat and looked inside down the pipe. The element is very close to the opening of the inlet pipe, just take a long handled screw driver and have at it. You can get the insides out with no trouble. Then mount it back where you found it and when they look with the mirror it will pass...

Oct 9, 2005 | 02:31 PM

vetsvette2002

Melting Slicks

Joined: May 2004

Posts: 2,505

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From: Willowbrook IL

St. Jude Donor '13-'14-'15-'16

Quote:

Originally Posted by HDFLH67

On your 1975, the catalytic converter is of the GM pellet design. There should be a large hex plug on the bottom of the shell. It is there to drain the useless pellets and refill with fresh pellets, no one ever did. Once you can get the pellets out, just replace the plug. You will have a noticably louder exhaust though. If you do not have the plug or can't get it out, just replace the converter with a newer design aftermarket high flow. This way you can still be running green.
Don