Catalytic Converter Removal

Catalytic Converter Removal
J

Jeepeagle

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Location
Georgia
Vehicle(s)
'78 CJ5 304, '94 ZJ 5.2L 4x4 , '04 WJ 4.7L 4x4
I bought my CJ5 from a guy in TN, which is pretty tight about emmisions. He had working catalytic converters, and whatever else was needed to pass in TN. Here in GA any vehicle over 25 years old or older is exempt from such tests.
What would be involved in removing the cats? Can I just cut them out and put pipes in it's place? Previous owners had custom dual exhaust routed to the sides, under the doors, and the cats are located behind the mufflers on the pipes.

Will removing these change the way my AMC 304 runs? It's pretty smoothe right now, starts right up, very little smoke if any. Thanks
 
well really federal law prohibits a car or truck with cats to change the fact weather it has them or not, but like u said here in NY 21 yrs or 25 yrs old you just have a safty inspection

as far as removing them go ahead take them off have a little fun. it will effect you performance you may gain HP loose torque or vise versa and yet again you may not get a change. the sound will be more mucile car era like. my 78 with a 360 doesnt have cats im running factory manifolds with the pipes ran out side the frame rail with glass pack purple hornie mufflers under the doors and the tips at a 45 degree angle right before the rear tire. i also do not have any of the emissions BS.

just be aware like i said its a fedral law to take cats off a vehicle with out replaceing. but it depends on how strict yyour state is.

you may have to tune your carb afterwards im not sure
 
If it's running good leave it alone. The cat won't hurt performance that much.
 
Jeepeagle said:
I bought my CJ5 from a guy in TN, which is pretty tight about emmisions. He had working catalytic converters, and whatever else was needed to pass in TN. Here in GA any vehicle over 25 years old or older is exempt from such tests.
What would be involved in removing the cats? Can I just cut them out and put pipes in it's place? Previous owners had custom dual exhaust routed to the sides, under the doors, and the cats are located behind the mufflers on the pipes.

Will removing these change the way my AMC 304 runs? It's pretty smoothe right now, starts right up, very little smoke if any. Thanks
Click to expand...



biohazard cj said:
well really federal law prohibits a car or truck with cats to change the fact weather it has them or not
Click to expand...


biohazard, you were mostly correct. The big thing is tampering with or removing OEM catalytic converers. Not all '78's had OEM cats. It then becomes the burden of the inspectors to prove that in fact it had OEM cats.

http://www.catalyticconverter.org/law/index.htm

But, there's always a but. From what you said the PO put the cats behind the mufflers. To my knowledge, no OEM cat has ever been installed behind the muffler. So they are without a doubt aftermarket cats.

I am going to agree with Longhorn, if it ain't broke, don't screw with it. IMHO If those cats aren't plugged or leaking, you aren't going to gain enough hp to justify screwing with them.
 
have we considered the operating temperature of a catalytic converter?? plenty high enough to ignite dry grass.:eek:
 
This is odd, as I understand it SEMA and a few others got together and sued over the fed tamper law, the judge found that the fed law usurped power from the states, not that violating the constitution matters much to the current bunch of a-holes in power:mad:.

Cats need heat to work, that is why they are near the manifold and always up stream of the muffler. My guess is they are for looks and have been gutted, if they are real cats they are probably not working very well. You may want to swing it by an exhaust shop first and have them see if the cats are doing anything. If they are working and you pull them, be sure to readjust your timing and carb to take advantage of the less restriction in the exhaust.
 
Don't know what it would do for a AMC 304 , but with my little ole AMC 258 i6 / 4.2l I6 it made a noticeable difference. Upped the pipe size to 1 7/8 and a hi flo muffler. Sounds better, and runs better. It will actually accelerate going up hill now. Needed to re-route the exhaust to get it farther away from the rear spring shackle bushing, so while the muffler shop was getting ready to fab the new pipe, I asked about eliminating the cat. Just had to show the muffler shop proof that it was older than '84. Also popped the belt off the smog pump cause it was noisy (bearings?). Soon as it warms up a little, gonna pull the rest of that junk out. Uh, no emissions test here.
 
sorry to dig up a old but, Jeepeagle im from tn and not once in the last 10 years have i ever had to smog or emissions check any of my vehicles:confused:. as a matter of fact the cats on my mustang were removed when i put my long tubes on. having said that cut the cats out. you will get a better sound and most of the time when you take out the cats you free up 3-5 hp. or if you are worried about emissions just hollow them out with some old rebar... not that i have ever done that or anything:cool:
 
IOPort51 said:
have we considered the operating temperature of a catalytic converter?? plenty high enough to ignite dry grass.:eek:
Click to expand...

Personal experience: I use hunt with a guy that drove from Houston to Fredricksburg, he parked his rig in some grass & brush.
He then took one of his rifles out of the bed put on his earmuffs and started checking his zero. When I drove up the Yota was fully engulfed in flames.:eek:
 
Back in 78, when they first started using cat converters, I heard several stories about off road vehicles bursting into flames but for one reason or another it never seemed to make any headlines. Kind of makes you wonder how they would have dealt with the latest Toyota brake issues back in the day.:cool:
 
This thread makes me think of a question...If you could put together a "perfect" exhaust system, which components would you use (Banks, Flowmaster, Borla, etc.)...starting with the header and working your way all the way back to the tailpipe???
 
MDJEEPER said:
This thread makes me think of a question...If you could put together a "perfect" exhaust system, which components would you use (Banks, Flowmaster, Borla, etc.)...starting with the header and working your way all the way back to the tailpipe???
Click to expand...

I would like the Borla two outlet headers for the AMC 258 i6 / 4.2l . I would have the local muffler shop do duals and put turbo mufflers on. This would make Minimal back pressure minimal noise.
 
Removed mine a week or two ago and did'nt get it on the dyno but does sound better, While I was at it I was trying to remedy the backfiring when you let off to shift gears(you are supposed to let off are'nt you?) and found the culprit to be in the "Air Guard" system(smog pump) so pulled all junk off and disabled the EGR while the hood was open and it now runs like a internal combustion engine should(before the feds get there mitts on it!)
Well the next smog test would be uglee for sure but with the new mopar system that will be going in you get to remove all that crude anyway(except the cat).
 
MDJEEPER said:
This thread makes me think of a question...If you could put together a "perfect" exhaust system, which components would you use (Banks, Flowmaster, Borla, etc.)...starting with the header and working your way all the way back to the tailpipe???
Click to expand...

Doug Thorley coated Tri-Y headers inside the frame with 2.5" pipes Flowmaster super 44's.:cool:
 
IOPort51 said:
Back in 78, when they first started using cat converters, I heard several stories about off road vehicles bursting into flames but for one reason or another it never seemed to make any headlines. Kind of makes you wonder how they would have dealt with the latest Toyota brake issues back in the day.:cool:
Click to expand...

The age of the lawyer had not yet come to pass.;)
 
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