I have a stock 77 Olds Cutlass 260 v8 with single exhaust needs new muffler and tailpipe. Yes I know before you say it, I wish was 350. It runs well and fun cruiser though. Thinking about removing original stock catalytic converter. What are thoughts on this, will I need to do any engine mods or is it as simple as removing converter? Also its rarely driven and in no inspection state.

 

What do you hope to accomplish by removing the catalytic converter?

 

I guess nothing really just thought 50 yrs old and thought about removing while doing exhaust.

 

I even thought about not even replacing muffler and straight piping off cat. The current muffler has hole in bottom bigger than softball and dont sound bad. LOL

 

The 260 in my 1979 Cutlass Supreme Brougham sounded better with no catalytic converter but an otherwise stock exhaust. If the converter is partially plugged, you might feel some performance gain.

 

I guess that was my thought just thought about removing in case of any obstruction and maybe a very small hp gain. I mean it seems to run fine now but not sure if clogged its 50 years old.

 

Would I have to change any engine setup if I remove? I dont see any smog stuff on engine. I think all they did in 77 is just add the converter for pollution control.

 

On a 77, you can simply remove the converter if you like. There's no extra air injection to it or anything that I'm aware of. Just make sure there's no emissions sniff checks coming down the pike. Some states just like to be dicks because...they're run by dicks. They'll make anything a big deal tied to a fine if they can get away with it. Technically, it's against federal law to tamper/remove emissions equipment like a cat converter, but normally something that "old" in their eyes may not be worth the trouble. You could just ensure it's clear through and through and emptying it out to ensure full flow through it. This way, if they just want a visual check, you'd at least pass that part. Removing a normally operating cat or not having a cat makes NO difference in the performance of a stock application, all things being equal. If it's plugged, that's a whole 'nuther peanut.

If you plan on keeping the car a long while, I'd at least figure out where a suitable replacement converter could be found.

 

I removed the cat on a '80 Buick Regal with the 3.8L V6. It did not make a difference in performance and it sounded like crap. Soon after I reinstalled it...

 

After I got beat by a coworkers Mercury Mistake, I mean Mistique, I knew power was down. Cut out the cat, definitely added more power. It was our high mileage 81 Delta 88. Being an Olds V8, it will sound great. Honestly add dual exhaust, that will add power and sound geat with the right mufflers.

 

Actually, there's no shame in being beaten by one of these if it was equipped with the Duratec 3.0 V6/5-speed manual combo. I had that setup in the Mystique's sister car, a Ford Contour SE. Thing went like hell.

 

Sadly, it was a 4 cyl standard, not so impressive. 1981 Delta 88 4 door with the Canadian non CCC Olds 307, very lean calibration, stock TH250C and I believe a 2.41 7.5" open rear end. No fireball with a half plugged cat, very weak. He just barely beat me, would not race me once the cat was thrown on the scrap pile out back of the Ford Dealer. We did have a V8 Taurus SHO come in for service, very interesting. Ford really got their act together in the 90's minus the aluminum head 3.8"s.

 

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Christian, thank you for chiming in. I was hoping you would.

Even if it's just for ***** and giggles, I would do it.

When we love our cars even little changes feel great. An oil change has me thinking my car got that much quicker...

She needs exhaust..., go dual with high flow cats.

There is another member either here or on the old Oldspower, or both. He played with his 260 powered vehicle plenty. And managed to get it down a couple of seconds IIRC. I cannot recall his name, but his avatar had 2 cars from post 1977 era on angle and was from Jersey, again IIRC.

Just don't expect much, and you wont be disappointed. The 260 never performed well when it came to quickness. The 1977 260 TH350 442 was good for about 21 seconds and 68 mph in the 1/4. If you are lucky you can get the 110 hp up to 130 or 0.5 hp per cube, with tried and true mods. But you will want to temper your expectations. All that and you may widdle the et down to 19 and mph up to 74.

Here is a nice original 260 that had the gears swapped to posi 3.42 on a 1979 Calais Coupe which weighs 500 lbs less than your 77. At the 2:00 minute mark he tests acceleration off the line.


On a bright note overall he's happy to have had her modded.

 

I had 3.42 gears behind a 260 with better exhaust, it wasn't that bad, could get out of its own way. Only had 100 psi compression across the board.

 

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Could she chirp on dead punch dry ground dead straight ?

First car I ever really drove was my parents 1970 Coronet sedan. It was stock original clean and healthy. Felt ballsy to me, auto 318 2bbl 230 hp gross. She had a nice healthy peel out under those same conditions I asked you about, while 3400 lbs curb, and skinny factory type tires. On turns forget about it, would absolutely rip and pop hubcaps off like the Charger in Bullitt. All those minimalist attributes surely helped because if the 1971 230 hp gross rating / 155 hp net is correct for 1970 as well. ( I figured it was 170 net). It's a 17 second car, and that's all it takes for natural wheelspin with good tread on tires, etc. But I'm sure the 260 lb ft peak at 1600 rpm has a lot to do with it.

 

I think it would spin the one wheel with the 215/75R14 tires. I wish I didn't sell the SP2P intake, would have went pretty good with on that 260. Like the last 403 I got, ran fine except low oil pressure, the crank was wasted on that one as well.

 

Spare the time and effort. It's probably fine. Only gain will be the loss of 30lb off the exhaust. Had headers and exhaust on my '77 with a 260 and there was a change in sound but that was it. If you're trying to make it a little faster, best off getting a 3.23 or 3.42 gear for it. Can use a whole axle from a 77-96 B body if you find one cheap. 89-91 with tow package came with those gears.

 

What about just removing muffler and going straight pipe off converter? The muffler now has hole bigger than softball and like the sound. Would it be much louder straight piped?

 

It may get louder at speed but you may still like it.

A little challenging to find a muffler delete Olds 260 on YouTube. Apples to oranges, but here is an Aurora with 244 CID V8 and muffler delete from idle to 6000 rpm. Then some driving under 2000 rpm then WOT. Video is short and to the point, under 2 minutes.


And a short of a 1983 Delta.

 

Those sound good