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cutting open the cat, taking out whats inside

84CUCV

84CUCV

3/4 ton status
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working on a friends new 88 k5. close to stock. cat is blocked. doesnt have the funds for a new one. going to cut it open in the am. take out what we can.. he need to pass inspection soon. short on funds tho

like to know this will not cause any other problems for the truck?? i know its not the right way, but he needs running good by late monday. thanks
 
Cut it on the top side of the seam that makes the two halves. Tack weld this to a piece of straight pipe. From underneath it will appear to be a good cat, but in reality will be a straight pipe.

Rene
 
thanks rene not sure where you mean. sure i will see it when i get under there in the am
 
Does he want a functional cat? You could hit up a junkyard for a used one. Otherwise I would just do what Rene said
 
84CUCV said:
thanks rene not sure where you mean. sure i will see it when i get under there in the am
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OK, I'll be more specific. The Cat is built in two halves, an upper half and a lower half. The crap inside is fitted, then the upper half is crimped to the lower half. Think of it like a breifcase...or a clamshell.

If you remove the cat and cut the lower skin off, then tack weld it to a piece of straight pipe it will appear to be a functional cat from underneath. Total cost is whatever your time is worth to you...plus a few cents worth of welding wire.

Rene
 
tRustyK5 said:
Cut it on the top side of the seam that makes the two halves. Tack weld this to a piece of straight pipe. From underneath it will appear to be a good cat, but in reality will be a straight pipe.

Rene
Click to expand...

only on this site will someone have thought of that :haha:
 
dfl701 said:
Does he want a functional cat? You could hit up a junkyard for a used one. Otherwise I would just do what Rene said
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You can't legally buy a used cat. Junkyards are supposed to remove and discard all of them before letting you pull parts.

Also, just want to remind you it is a FEDERAL crime to tamper with the emmissions equipment.

I would guy it with a prybar, way harder to tell its been tampered with.

Don't get caught.
 
dhcomp said:
Also, just want to remind you it is a FEDERAL crime to tamper with the emmissions equipment.

.
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wondered how long it would take for this to show up :p::D

and yeah, funny thing is a vehicle doesn't really need them, imagine that.

My mothers truck has a hollowed out Cat (burnt out) and it passes emieeions very easily, everytime, no other mods were done to the motor either.

Disclaimer* i did not modify this Cat, it burnt out for seom reason on it's own, had bad rattling in the exhaust system one day, replaced the blown out muffler with a newer model Chevy truck unit and that's when i noticed the hollow Cat, sounds alittle weird, alittle "canny" but it's still there, so leaving it alone for now until the (spare) funds are available for replacement
 
84CUCV said:
thanks for the link. really? cat doesnt do anything??
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The purpose of a cat is to use a catylist to convert CO emissions into CO2. The idea is that the catylist gets really hot to support the chemical reaction. In an ideal world where engines burn every ounce of fuel put into the cylinders, there would be no CO emissions, but since that is never the case cats are inplace to reduce those effects. Unless your air/fuel ratio is dead on at all times its pretty expected that you need one.

Do you need one to run the engine, no. Do you need it to pass emissions test, yes.
 
I have actually just taken the tubes and cut them off the ends and rammed a straight piece of tube though it. Reason for this is I had a buddy who used to work at an inspection station somewhere else, I think it was like Maine or somewhere. They used mirrors to make sure the cat hadn't been tampered with.

Looks like a perfectly good cat but its just a straight pipe through it.

Truck was going to Utah, happily no emmisions where I live
 
Chevy305 said:
Do you need one to run the engine, no. Do you need it to pass emissions test, yes.
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As i previously stated, this particular truck does NOT fail emissions with this hollowed out Cat and passes a very strict test, it DOES need to be there visually for this inspection, i agree on that, but not always needed for sniffer test, of course this engine is very well maintaind and everything else on it is in working order, BTW, no smog pump either, just a Cat and EGR from the factory on this one :laugh:

and i didn't say they are not needed as in, not at all, alot of older carb'd engines will benefit from them, due to the not-so-perfect regulation of the fuel being dropped in the intake. Helps with the vapors coming from the exhaust.
 
79rustyk10 said:
IM so glad I dont have to deal with the f-in BS emission testing yet.
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we currently do not have to deal with this any longer either, I had to remove the factory exhaust on my burb a few months ago, from a wheeling trip that didn't turn out to good, ended up crushing the crossover tube and the one feeding the into the cat, too much backpressure on the motor, started burning oil like crazy.

Removed it all, custom built a true dual setup, obviously no cats, as i didn't have any for replacement, and using Ford Cobra Mustag mufflers :doah: Breaths alot nicer, no major problems with fumes, and now don't need to test it in the new city :D

I also don't really drive it much either, so i'm not too concerned with the exhaust setup anyways.
 
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