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Gutting only one precat

1783 Views 12 Replies 8 Participants Last post by  bantamcougar
I was thinking about gutting only one of my precats, since i think it might be easy to do and wont take much time. I searched for anyone that may have gutted only one, and found nothing.
Has anyone gutted only one precat? Will it hurt the car? hmm let me know if anyone does know of anything. thanks
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Ive gutted 2 of mine. The first cat that they say you have to get a coat hanger or bucket handle with to gut I wouldnt even bother cause it was so okward to get to gut. Youd be better off just cutting it open with a welder or summin. The last 2 wich are the easiest I barely could tell a diff. after wards, so the first one try your best to gut!
Ok, thanks. I dont know what i am going to do. I think im just gonna wing it. im just a little scared about the parts from radio shack. somehow i know i will mess that up.
Oh, yeah, does anyone know what happens if you dont get the mechanism from radio shack and wire it to the exhaust sensor?
yeah, you'll get a check engine light for o2 sensors... that's about all.. you might run a little rich/lean too, which isn't that bad..

if you don't think you can make the MIL Eliminators, you can buy them online.. through ebay, or through they're $30 a pair there. I say it's better to spend the $5 in parts and make it yourself for cheaper..
Alright, here's the deal:

i'd either gut both precats or none. It isn't really that hard.

First off, there seems to be some confusion with which are the precats. The precats are attached to the front and rear bank of the engine. The piece that connects those two is the y-pipe, not a precat.

In a nutshell, this is how you do it. Disconnect the battery and jack up the car. Remove the y-pipe, which would be 2 nuts on the front precat, 2 on the rear precat (the whole bolt may come off, which isn't a big deal), 2 at the catalytic converter and one nut that simply holds the whole y-pipe up. Remove the O2 sensor at the bottom of the front precat.

Use a screwdriver to gut the rear precat. Drill a 1/4" hole in the bottom of the front precat at the bottom of the bend, in line with the straight section of the precat. Use a bucket handle attached to a drill to gut the front precat. Start the car and blow all the crap out of the precats. Put the y-pipe back on and reconnect the O2 sensor. Hook up the MIL eliminators.

Done. There are how-tos on how to do it elsewhere that are more thorough than this description.
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expect to spend about an hour on each precat, maybe even longer on the front one.

Ok sounds good, thanks for the input. yeah i got a great HOW-TO off some website. Im just kinda nervous thats all, im just gonna wing it, spend all day on it monday and see what i can do. Im very interested too see what kind of difference it makes.

Hey if i screw up, i can just B!tch to my mom about how headers are the "only" way to fix it, then maybe she will buy me some. (def not)

Thanks for all the help, i will let you know how it goes on monday. thanks guys
what website did u use,,, for gutting the precats
IIRC there's a how-to on the MC-NECO and on Just make sure you let the nuts/bolts soak in plenty of PB Blaster. If you don't have any you can get it at any auto parts store for about $5. Just hope you don't snap three out of 7 bolts like i did. :biggrin:
how do you patch that hole in the pipe? just curious if u left it or what
Put a bolt in it. Tape a bolt into a wrench, and stick it through from the INSIDE. Then put the nut on from the outside and crank it down.

Or you can use a typical plug for plumbing purposes, and tap the hole to accommodate that.

I tapped mine and, lacking a plug, plugged it with a grease fitting! So now I can lube my manifold... ;) But I can just get a plug and swap it out anytime I want, now.
Gutted my precats today, came out well. Just a tip for the front precat. Use a circle saw (1 inch or bigger) instead of a drill hole. this will be alot easier to get all the honeycomb crap out. Your going to have to weld it back on though, so dont do it unless you have a welder handy.
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