cor66vette

I would like to replace the cat converter on my '75 with a plain straight pipe- smog pump was removed when crate motor was installed. I'm hearing rattling in it and I'm concerned it may cause a problem if something large inside gets loose and interferes with the exhaust flow. Is there something "standard" I can install in place of it? Muffler shops scoff at me because of emissions laws. Also, are there any negative effects performance-wise doing this. Thanks

'75

Are side pipes in your future? That would certainly eliminate the cat.

terry82

lots of choices to replace cat with hp new style cats ,,,,but in the mean time take cat off,take a long metal rod and knock all the bad stuff out .you now have a test tube .

cor66vette

As much as I like side pipes, no- they're not in the plan. I just want to address the possible clogged cat issue. I don't intend on doing a whole lot to the car other than enjoy tinkering with and driving it like I am doing. The only big thing I did was convert the trans to 4 speed. The PO swapped the L48 with a GM crate 350/290. I do plan on getting a 69 - 72 one of these days, in which case I'll sell the '75, so I don't want to put too much money in it for "frills". The '75 has been very good to me since I bought it about 5 years ago.

Thanks for the comment.

cv67

are you still using the EGR?
A modern day cat is worlds better doesnt hurt performance and eveyrthing will work the way it should
You may wanna toss your muffler its probably full of cat material and weighs 30 lbs

Furioso

My '94 failed California Smog and there was a crack in the exhaust manifold so I added headers and these ebay catalytic converters:

For 1992-1995 Chevrolet Corvette Catalytic Converter Walker 18455MV 1993 1994. Oh. Cost around $300. for the pair.

ntfday

Drop all the garbage and run true duals from a 74 which is what I did on my 76.

KenSny

Yep, that's the way to go.
EXCEPT the OP doesn't want to spend money, So he should just gut the existing cat as stated above and not worry.

interpon

agree..i thought forever on test pipe..cannot find anywhere..and not cheap..about 80 bucks..this assumes you also can not hack the pipes to get converter off as space is tight..
went allens exhaust true duals. And my cat worked and original..
https://www.corvetteforum.com/forums...79-4speed.html

mrvette

OP, here in Florida there are many shops that will chop out that cat for the scrap value and put in a test pipe for next to nothing, welded in, easy as pie, job don't take but maybe 30 minits time, guy knows WTF he doing that is....