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Discussion Starter #1 (Edited)
I've got a 93 EB 5.0 that has two cats, my question is if I only run one cat will I still pass smog In california? Any one i cali tried this?
 

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I've got a 93 EB 5.0 that has two cats, my question is if I only run one cat will I still pass smog In california? Any one i cali tried this?
Officially, No.

Cali CARB rules state that you may not change the number of cats or the size of the pipe or change from a single to a dual. All cats must meet CARB certification.

After the Cat you can do anything you wish as long as it meets Fed rules and local noise rules.

Your pre OBD-II vehicle can use any cat, header or pipe tested and certified for your specific engine.

"It is, also, legal to install an OBD II compliant aftermarket catalytic
converter or header on non-OBD II equipped vehicle provided that the engine
displacement and equivalent test weight (ETW) of the non-OBD II vehicle
do not exceed those of the vehicle model with the highest engine
displacement and ETW of the vehicles listed under the Executive Order
(EO) for the particular catalytic converter or header model."

For example, if your 1993 Ford truck has engine displacement of 5.0L and
a test weight of 5000 lbs., you can install an OBD II compliant after
catalytic converter exempted for Ford trucks on the vehicle, if one of
the trucks listed under the particular EO has an engine displacement of
5.0L or greater and an equivalent test weight of 5000 lbs. or higher.

You can roughly estimate the ETW of a vehicle by the following formula:
ETW = Curb Weight + 1/2(GVWR-Curb Weight).

As, Redwagon said, if your tester doesn't do a thorough job you may pass. But, if he sees a lot of shiney new parts and decides to take a closer look. You could be off to see the arbitrator.:box0715:

My advice is buy only CARB certified parts with sticker to prove it.

On a different note. ;) I heard of a guy that welded flanges to his cats. When he had to smog he unbolted the straight pipe between his first cat and muffler, and bolted in his second cat.:goodfinge

Hope you find the above information helpful.
 

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re: cat

the vehicle came with 2 cats.if you took off the precat, i, as a smog tech will pick up on that in a heart beat and would be forced to fail it under "missing"/or "modified" cat conv.

dont get me wrong, i do not want to fail a fellow wheelers truck, but the punishment is extreme if i let it slide.

i would recommend you replace the main cat, and leave the precat alone. smog it, and then _______________ ;) for 2 years. just keep the OE stuff for smog purposes.

you can email me if you would like to talk about it.

good luck
 

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re: cat

evan-

when i get to the shop tuesday morning, i will check what my reference book says in comparison to your emission label under your hood. the label always supersceeds the book. if you remove the precat, it can pass exhaust emissions, but will fail visual. check the thread tues morning.

any modification has to have CARB EO#_____ in order to comply. removing the precat and cat, and installing 1 high flow cat DOES NOT qualify. the precat HAS to be there unless under the EO it states otherwise.
 

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Discussion Starter #8
Well here's why I ask, Guess I should have put this in to begin with. first to save money, second because I want to redo te whole exhaust and was wondering about preformance. Can anyone recommend a bolt on kit or part #'s including cats that have worked well for you. affordablity is important.
 

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cat

what are you trying to gain? power? a simple cat replacement wont do that. if you want a noticable increase, its gonna take intake, throttle body, headers, then exhaust, such as a high flow cat.(im not a believer in high flow cats btw) the truck weighs a lot, the hassle of emissions vs the power increase doesnt make it worth it. for under $200 you can have a cat installed, just leave the precat alone, even if its hollowed out, the main cat will do enough by itself.
 

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I'm surprised you havent been flamed for not searching... anyway, there are more threads on this if you want more info.


the vehicle came with 2 cats.if you took off the precat, i, as a smog tech will pick up on that in a heart beat and would be forced to fail it under "missing"/or "modified" cat conv.
The first one's not a precat, it is an oxidation cat, the second one is a reduction cat. Modern high flows have those 2 parts in one cat.
 

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Discussion Starter #14
I'm talking about gaining power, I didn't expect to gain power by leaving out one cat, I expected my wallet to gain power by not buying one cat if I didn't need it. As far as power I'm planning on replaceing everything Cat to exhaust including (probly) 2 1/2" pipe? What diam. pipe would be best for a mostly stock 5.0? I'm thinkin magnaflow exhaust, but I don't know much about cats, so any help would be great.
 

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i called the local muffler shop and they will cut out the 2 cats and put in a high flow one. They wont do anything illegal either, so i trust them on this. I want one just because i probably have clogged(original cats) so i probably might feel a tiny bit of power, and more importantly it will complete my sound system to sound extremely mean.
 

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. Can anyone recommend a bolt on kit or part #'s including cats that have worked well for you. affordablity is important.
Stay away from kits. It's cheaper to buy individual parts. There are a number of threads with lots of opinions, but you'll have to decide.

As far as power I'm planning on replaceing everything Cat to exhaust including (probly) 2 1/2" pipe? What diam. pipe would be best for a mostly stock 5.0? I'm thinkin magnaflow exhaust, but I don't know much about cats, so any help would be great.
Unless you change your exhaust manifolds to headers, having bigger pipes and high flow cats and muffler, will gain you nothing except better sound.
Based on the email I got from CARB, which I quoted in my prior post, you can pick any component either OBD-I or OBD-II certified for any year 5.0L or 5.8L bronco. And, anything goes after the cat.
 

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Discussion Starter #17
Headers are on the list as well, but I figured on doing some reading on that subject. I'm leaning towards shorties and something affordable, thats as far as I've gotten on that one.
 

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correct-late model man

I'm surprised you havent been flamed for not searching... anyway, there are more threads on this if you want more info.




The first one's not a precat, it is an oxidation cat, the second one is a reduction cat. Modern high flows have those 2 parts in one cat.
this is correct terminology. the generic term is precat, but really hes right, its an oxidation cat. i wasnt aware of an aftermarket replacement cat that is acceptable. i would have to see and verify CARB EO# to pass the truck on visual. any1 have those EO #'s?

thank you for the correction late model man
 

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this is correct terminology. the generic term is precat, but really hes right, its an oxidation cat. i wasnt aware of an aftermarket replacement cat that is acceptable. i would have to see and verify CARB EO# to pass the truck on visual. any1 have those EO #'s?

thank you for the correction late model man
No problem;) However my cat knowledge stops here. I've always been told that any CARB legal high flow cat is acceptable. If it is CARB legal it comes with a EO # right? Say my cats fell off, do you have to replace it with the stock dual system or can you use a newer single design?
 

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Just curious, but what if I wanted to change to a dual exhaust system on my 86 5.0 EFI? Is it legal and would you have to have CATS on both sides just after the headers?

Thanks

:enforce
 
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