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'75 Catalytic Convertor

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Old 10-08-2005, 05:41 PM   #1
HDFLH67
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Default '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!
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Old 10-08-2005, 06:01 PM   #2
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I'd get a cheapo and gut it by running a straight pipe thru it - No restriction.....
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Old 10-08-2005, 06:59 PM   #3
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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.
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Old 10-08-2005, 08:11 PM   #4
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Quote:
Originally Posted by HDFLH67
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!
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...
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Old 10-09-2005, 02:31 PM   #5
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Quote:
Originally Posted by HDFLH67
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!
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
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Old 10-10-2005, 08:52 AM   #6
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Bash the center out, it will pass emissions no problem.
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Old 10-10-2005, 10:30 PM   #7
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Thanks All!
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Old 10-10-2005, 11:36 PM   #8
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some have a round plug knock it out clean and replace with a freeze plug a little grinding on the plug is needed
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Old 10-11-2005, 04:59 PM   #9
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Just do it right so you don't have to worry about it.

http://www.ecklers.com/product.asp?d...XLJBBUTA8E97K6

BigBlockk

Later.....
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