How does one unclog catalytic converters most easily?
 

I just took off my airpump and sealed the tube. I did this not really for performance or aesthetics, but more because of the noise of exhaust coming up through the airtube making a loud put put sound that can be heard in the cabin with the soundproofing now removed.

I have a pair of aftermarket cats on a crappy summit h-pipe welded down right before the crossover tube, So I could technically get at the back of the cats if necessary. Could I run water through them? They're not clogged (yet), but I suppose they will be shortly.

What exactly is in a catalyst anyway and what would damage them?

They can't be repaired. Once they clog, they are junk.

What they said. And clogging will be a MAJOR hinderance to power. Hell, with what you said, it already IS a major hinderance to power. Replace them with high flows. If you don't want to spend that much money, get them off of there and run a pipe of the same diameter as the in and out of the cat through the center of it so it'll be like straightpipes...but that's if you don't have to worry about emissions. Note..it'll be much louder and stinkier with this..but if you're like me..that's a good thing!

Re: How does one unclog catalytic converters most easily?
 

Yeah, buy new ones. Their toast!

This explains why I'm always seeing uneven readings on my O2 sensors. The airtube only fed the passenger side cat by bad design. The drivers side sensor seems dead half the time. Probably extra back pressure there.

Will running it lean(ish) keep the cats from getting clogged up? I dont race much in the winter anyway

With converters, running excessively lean will cause the catalyst to become brittle from the heat, breaking up and traveling downstream with pieces either turning sideways in the pipes and clogging your system, or if you have a chambered type muffler a broken-up piece can get trapped inside, rattling around and hindering exhaust flow.... running excessively rich will cause the catalyst to melt from contact with unburned fuel, closing the very small passages that the exhaust has to travel through, also rendereing your system ineffective...

Running water through them isn't going to accomplish anything. It would be hard for me to determine whether they are still good or not without actually seeing them, but you need to get the car properly tuned or remove the converters all together (gut them or find someone with a welder that can weld a couple pieces of tubing in where the cats were... you could also 'gut' them, but the sound of a hollow converter is a strange one.

How does one unclog catalytic converters most easily? By unbolting the rear flanges of the h-pipe, getting a long metal prybar, punch, etc. and using a hammer to beat the living hell out of the catalyst (starting the car up every few moments, reving past 3-4k rpm to clear out what has been broken up) until nothing remains inside the converter shell. I can't describe the sound of a hollow converter, but if you can accomplish the above task, you'll know what I'm talking about. ...hope this helps some :)

i have done the above before..it sucks...its a pain...whats inside? its like a honey comb inside....there is also screens inside you have to rip out....i personally dont think its worth the time or effort

If at all possible, run a pipe through instead of gutting the cats. With them hollowed out, the air expands in the empty 'chamber' and when it's forced to squeeze back down into the exit piping, it creates a hell of a lot of turbulence and backpressure.

Well, I actually need the cats there because I need to get a sticker at some point. I'm counting on the fact that no one ever opens the hood during inspection. I'm planning on reconnecting the cross over behind the heads, cutting off the valve on the end and diverting some exhaust gas into the fender. I'm probably going to have to put the airpump back then

I dont know.... what kind of chance do I have with no emissions controls except a pair of cats and running a carb? Absolutely none, right?

Probably none. ;) Emissions checks are so picky...I know v6's that were EFI, had a cat on them, but were out of tune so they failed emissions.

I'm not familiar with the laws in Mass., but you wouldn't get in the door out here. Believe it or not, you can get away with a lot here, too, but you can't put a carb on a vehicle for which that wasn't a factory option.

Either way, replace your cats. Don't screw with them.

Take care,
~Chris

Hey Chris, Where do you get your smilies from?
Caymon

Hey man, Im in newton now and the best route, is to just get an OFF ROAD H pipe... and keep the CATTED stock pipe and switch them when it comes to sticker time... its ONCe a year... so you can afford to spend a day crawling under there and switching them... cause technicaly it's just 8 bolts.. they might be a bit rusted on.. but it can be done... it depends on where you go for the inspection... but all places put you on the DYNO... so you cant avoid emissions.... though i used to go to a dude in waltham, some russian guy, he wouldnt even look at the car, he put it on the machine and it was good to go... though he closed down (I wonder why) so I have to find another guy who's not so scrutinizing... but like I said, you cant fool the machine.. unless you have a real good relationship with your mechanic.. in wich case.. they have ways of MAKING it pass... :)
-as

I have a perfectly good factory h-pipe sitting in my attic and have absolutely no use for it whatsoever...hmmm...to bad your so far away...

I wonder how much exhaust gas I will have to divert to get my car to seem clean. I was thinking of getting clever and

A. Reattaching the cross over pipe behind the heads (cutting off the one way valve) and diverting the gas somewhere (fender?)

B. Clamping a hose onto the exhaust pipe airtube (now under positive pressure) and likewise diverting some more exhaust elsewhere.

Do I need the airpump or will these tricks be enough, ya all think?

I know an open minded mechanic, but it seems that in these dark days, even the open minded mechanics are starting to get cautious

without an airpump, how are you using the tubing that goes to the heads and the h-pipe? Your supposed to be pumping clean air into these ports, not taking exhaust out of them...

sounds like you are going to create exhaust leaks and think this will help you pass emissions?

the problem with "THE MACHINE" is.. it's expecting certain readings... and if they are off you fail... simple as that... generaly the machine can tell if theres a leak... not like it looks to see.. but I guess if the mix is OFF somehow... it's tough..since we're forced to deal with the MACHINE, you might as well put the air pump back on, it's not robbing you of any noticable power and do a pipe switch once a year, if you want, I'll come help ya some day
-as

Ok, here is the other idea I had...

I've got the airpump and I've got the tiny stock alternator pulley left over from my underdrive pulley install. I've pretty much got the pulley drilled to fit the airpump, so the airpump spins like there's no tommorrow. Will blasting incredible amounts of air solve the problem?

Should I blast the cats or the heads if given the choice or should I blast them both with air.

Why not just build a bridge out of matchsticks and drive to England?

Dude, you're making this so much harder than it needs to be. Stop tweaking on your car and do it right. It will save you time, money, and headaches, and won't cost you horsepower.

:)

Take care,
~Chris

P.S. Don't do the bridge thing either. Probably wouldn't work. ;)

So you truly feel that a carbed mustang could pass a sniffer with a good pair of cats and an airpump if I hooked it back up the way it was before with no mcguyver stuff.

(oh matches...well, I could build a huge match barge, yeah yeah and take all the match heads off and put them into a huge metal trashcan, which I lash to the back of the raft and ignite and use like a JATO...)

Yes, i think you would easily pass the sniffer, but i don't know what the laws are there regarding a carb on a car when that wasn't a factory option.

My guess is, if it passes the sniffer, then you'll be all set.. depending on your mechanic.. .if you have a good relationship with him he most likley wont bust your balls... or if he's just lazy, then you'd be fine... if the machine likes it.. then i would imagine it wont be a big deal. Though, I would guess that the rules for inspection would state something like, if it wasnt an option then then it shoudl fail or something.. technicaly your flowmasters should fail, since they are louder then stock.. but most people arent in the ball busting business..
-as

no, flowmasters have nothing to do with passing inspection. if its safe(brakes, lights, etc...) and it passes emmissions with the sniffer, you should be good to go.

they can do a visual and make sure no emissions equipment has been removed, but most places arent that concerned with the visual. dont sweat that part.

funny stuff
 

I had to laugh at that one. Never heard of someone modifying the smog pump to become a small jet engine! :D

Good luck though. Let us know how it goes.

It blows so much air that for a moment, I thought of sealing a funnel to the top of the carb and using it as a poor man's supercharger. Then I smaked myself in the head and just removed it.

[Scratches head, deep in thought over the supercharger idea]... :D If I had a smog pump that is.... :cool:

Well, you get an "A' for effort, but your ideas are poor, very poor.

theres no cheap way to make a nice, clean, well built car. Do it right or dont mess with it at all.

oops.... I guess smog pumps we'rent meant to operate at 15,000 rpms for extended periods of time. It pretty much melted. The inside of it is all fused together. I knew something was wrong when I saw the thick plumes of smoke billowing from under the hood. Basically, the pump had siezed and the belt was being dragged over it, melting the belt rubber too.

Everyone can now say... "I told ya so"

Either way it WAS cool. It sounded like a propeller. Well, I'm off to the junkyard.

isnt the best way to clean out cats to use leaded gas? i hear it works wonders...:D

other then a lead additive, where ya going to find leaded gas these days?

as as for the pump.. that's pretty funny.. I wish I would have seen that... I wonder what a junk yard gharges for a pump...
-as

I have a air pump for sale if your interested. Its from a 93GT and in excellent condition.

Ha Ha!

Nothing a mallet, a file and some sandpaper couldn't fix (ok, a lot of sandpaper). I not have a slightly warmed over, but "custom" airpump with lots of clearance inside. With more wisdom, I reinstall the original pulley

Really, lead additive helps? Why is that? I figured it would clog the converters.

Is there any reason not to simply pump air only to the rear of the heads? Saves me some tubing.

Lead additive..HA!!!!! Lmao... You'd be running like 130 octane. Not only would you fail emissions because the sniffer would pick up all that lead and crap, which is very toxic by the way I'm sure, but your engine would probably take very very poorly to it..might damage components. These cars weren't meant to operate with lead...period. And being that it's illegal to use leaded gas, I highly doubt there's a lead additive..except maybe in like, Afghanistan...but then who has a car in Afghanistan?? :D

uhh...you guys know that little dingy planes run on leaded fuel...the stuff is REALLY high octane...ive been with my brother a couple of times flying and usually he has to fill up...so just bring your old pre-cats muscle car to a small-scale airport and fill up for $30...still not too good for the car though..lol

but yea...you can get leaded fuel :P

If I hear little popping noises in the exhaust on deceleration, should I be worried? They're not loud bangs, just little "doof doof" sounds when I'm coasting. The backfires sound like they are coming from the headers rather than the cats. Is it safe to ignore them or is something going to blow apart?

Probably has something to do with me pumping air directly into the back of the heads with no dump valve.

Backfires are normal. My 91 GT is an EFI car with headers, an X pipe, and flowmasters, and it backfires on deceleration. Pretty much any car with exhaust mods is going to backfire on deceleration, especially these.. No worries, unless it backfires during acceleration or cruise or the backfires sound like they're going to rip something apart.

Btw, jonathon, I totally forgot planes use leaded... I should've known that...I've flown several single engines and wanted to be a pilot at one point in time. But that was when I was 14 and as far as cars went, I didn't know a turbocharger apart from a power steering pump. No joke.

leaded
 

They sell lead additives at your local autoparts store. So, who's the..."Lmao"??

J/K :D

Do they really sell lead additives??? If they do, god help us all.. Apparently very old cars are exempt from the 'don't use toxic chemicals that destroy the earth and kill us all' laws. Because LEAD IS POISONOUS!! (And no, emissions don't kill us all, only destroy the earth. ;) )

I think I'm all set with the lead, in that case, I sniff enough fumes as it is pulling heat off the top of the headers to heat the cabin

Whoa, having the airpump firing into the back of the heads changes the exhaust tone! It sounds like a constant growl. I might be mistaken, but it seems to be quicker on the uptake now...

They sell lead additive for OLD cars... anything before about 1970 in it's ORIGINAL form would be designed to run leaded gas... you can convert most engines to run on UNLEADED but using hardened valve seats and stuff.. but it you wanna "keep it real" you'd need that additive... now, weather it's actulay LEAD or a synthetic that ACTS like lead, I dunno.. it's basicaly there as a lubricant for engine components...

as for the exhaust grumble and poping... that's normal liek the other posts said... generaly its caused by oxygen getting into the exhaust system and re-igniting your exhaust...it's more previlant if you have bad exhaust leaks... if you are nice and sealed up you'll still get it cause of your air pump I guess.. though I kinda like that sound... but that's just me
-as

They sell (or use to sell) the 110 octane leaded stuff here at speedway (orlando, FL). They will only let you dispense into a container. A few times I mixed it with 93 octane (about 50/50) and cranked my timing to about 16 degrees. In cold weather it makes a very noticable difference. Never took it to the track this way.

Well, funny thing is I tried setting the timing to 16 degrees, but the car just wont stay at 16 degrees!

I would set the distributor to 16 degrees with my light, tighten the hold down clamp, recheck and it would be at 16. I would drive it around, come back, check it and it would be back at 10. I set it again, reclamped, drove around and when I looked, it was back at 10!

The car is possessed!

I never knew these mechanical distributors were so stubborn.

I've always run 87 and never had any pinging at all no matter how hard I pushed it.

Did you remember to remove the SPOUT connector before setting base timing? If you don't, your changes won't hold. I have mine set at 14 degrees. If I put anything lower than 92 in my car, it pings. Removing the SPOUT severs the computer link during timing changes. Most cars running 93 octane can be bumped up to 14 degrees before they start to ping.

Think I can get away with 12-13 degrees of timing running 89 octane?

Before I had this possessed distributor and I actually had a computer, I would run between 14 and 16 degrees using 87 octane and never had any problems. I guess I dont beat on it hard enough to get good detonation going

4-6 degrees advanced over stock on crap gas? You must be either deaf or very very lucky!!

timing/gas
 

If you advance the timing at all...you'd be stupid not to run at least 91 or higher octane.

Gotta check my timing..don't know what it's set at but it's hard to start the thing, it misses when I punch the gas, and it's getting 89 octane.