I have a '88 IROC with a single cat, 350, 700R-4, all stock. My car has almost 150K miles on it. I noticed this morning when I started my car up and started driving down the street I could hear what sounded like metal rattling under my car. I think either my cat might have come loose because Austin,TX is pot hole heaven or possibly the ceramic inside has come loose. Is a cat supposed to last longer the 150K miles or 13 years in my case? If I do need to replace I am thinking of going with a CatCo Cat from summit. Since my car is all stock I dont see the need in buying a random tech plus summit has the CatCo's for $59. If anyone can shed light on this top I will really appreciate it.

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Poor college student(donations welcome ;0) with an all stock 1988 5.7L IROC-Z Hardtop, Auto. trans, white ext. w/gold accents (soon to be silver), black custom cloth interior, 4-wheel discs and G92 pkg. Car is dead stock. Has only standard Z28 power options and all the IROC performance stuff you could get. No pwr. seats, mirrors, or rear defrost.

Best run: 1/4 14.90 @ 92.7 MPH

See My Car here: http://zap.to/chevyguy1969

#3 Gone but shall never be forgotten. Long live the legacy of the man in black. RIP Dale Earnhardt "The Intimidator"

 

I dont know if this is true but my friend said that cats normaly only last about 80,000 miles . If the inside of your cat is loose just gut it and save yourself $60 .

 

I dont want to gut it if its loose. I have heard that TPI engines need some back pressure to run properly. My car is all stock and its my everyday driver. I really would like to replace it instead of gutting, if thats even the problem. Does anyone else know what it might be? I guess I will jack it up this weekend and go under it and shake everything and see what happens.

 

It also depends on the way your engine is running and if the cat was designed for the engine. I had a cat last 130k and then on my 91 had a cat last, are you ready, 4 days!!!! Muffler shop gave me a cat that was for a 5.0 and smaller. Anyways, the catco cats are good cats.

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'91 Z-28 5.7, SLP 1 3/4 headers, 4 inch Mufflex/Flowmaster cat back, gutted cats, Edelbrock intake, 8.5mm Jacob wires, MSD Blaster coil, S&W subframe setup, Jacob Pro Street Ignition, complete Kenwood system.

 

My cat lasted 9 years @ 145,000 miles.
Actually it was clogged, the car stopped running.

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1986 Black/Gold LG4 Z28
Original Owner, 200,000+ near trouble free miles.
Mostly Stock.

1995 Dark Red Metallic Corvette Coupe Original Owner

 

Unless you are planning to rip out the ECM- replace the cat- the car's closed loop system was made to use a cat. This is kind of like street racer who removes the EGR valve and claims he got extra horses, when in fact the EGR valve has nothing to do with full throttle operation (EGR valve does not operate at full throttle at all) Dumping the cat, for your daily driving purposes, is not a feasible option. Now if you want to build an all out asphalt monster, gut it! (along with engine, ecm, etc.

 

how does it affect my TPI on my 305 if i have a cutout (before the cat) open then ??

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Arthur-
1985 IROC Restoration In Progress
http://www.thirdgenfbody.com/projiroc/
Member # 98 of The Las Vegas F-Body Association
www.lvfbody.com

 

If you have a cut out before cat it is like having dumps. You won't get optimum fuel mileage or good emissions control- but I'm sure that doesn't matter if you are running the quarter mile, right?

 

how can you tell if its good or bad?

 

To tell if its good... When the exhaust system is cold (VERY important) smack the y-pipe very close to the cat. If you hear anything moving around in the cat, its bad. To check to see if its cloged, disconnect the intermediate pipe from the cat and shine a flashlight into it. If you can see through it (you have to be looking STRAIGHT down the cat or you won't be able to see it correctly) you are good to go. That will give you a good idea of the condition of the cat.

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• 89 Formula 305 WS6
  SFC's, LCA's, Air Foil
  Spohn Panhard Bar
  Flowmaster Cat Back, Tranny Cooler
  A/F Ratio Meter (not a mod but it sure spurs interest)
  Trans Temp Gauge
  Most "Free" Mods
  3:73, Zexel Torsion Posi
• 90 Eagle Talon 2.0
  (Winter Beater)
  Mods? Um, no

 

wahhhh the bolts are rusted and looks like they're about to fall off!

Can someone give me measurements of them so I can get a new set at the hardware store?