My new 78 car stinks when starting up in garage. Found cat was gone and test pipe installed. Will an aftermarket cat stop the initial start and idling smell? . Which is a good one to buy and from who?

 

I read the title and thought you had your cat's litterbox in the garage....

 

I still have the factory cat from my car, but I removed it after she got paw prints all over the hood.



Adjusting your idle mixture, choke, timing, and making sure your charcoal canister is working should help with the smell though.

 

Most of that is choke smoke. I highly doubt the charcoal canister can do anything about that.
putting a cat on will not stop it from running rich on start up. The smell will change, but not go away. Actually the choke smell with a cat stinks worse in my opinion.
The cat will of course hurt your performance.
As above, try tuning your carburetor. But seriously, it's a carburetor with a butterfly choke.
Best thing you can do, open the garage door before starting a old carbureted car.

 

If my cat eliminated in my garage, … (you don’t want to know).

 

Open the doors and get a fan

 

Cats aren’t worth the space they take up…..

 

Now THAT"S funny!

 

Sometimes they do. 1, 2, and mice, so I can get photos like this.



My EVs smell like nothing. But my C5 smells almost like nothing, likely due to it not leaking, and not having a carb. I leave the garage door open for an hour after I park the C3. Don't need to do that with the C5. Perhaps an LS swap would solve your problem?

 

I actually like the faint smell of gasoline and unless there is Too much of the smell in the garage where it becomes a Fire hazard. Many years ago I had a pin hole leak develop on my fuel supply line. The hole was literally a tiny pin hole and slowly sprayed gasoline over an area where it would evaporate before being seen or making a puddle of gasoline. This hole was allowing air to be pulled into the mechanical fuel pump and causing other issues.

The biggest and most dangerous problem was the "almost invisible" gas puddle that was constantly evaporating leaving a strong smell of gasoline. Gas fumes are very dangerous, if you have a strong smell of gasoline in the garage then I would use a fan (outside the room) to blow fresh air back into the corners of the garage. I would operate nothing that uses electricity until the fumes are cleared out of the room. I also believe in multiple Fire extinguishers in a garage so you always have one handy and within reach.
Good Ventilation is a must in any garage!

My favorite is the smell of the YAMA-Lube 2 stroke oil that my motorcycle uses to be able to run. I keep the Yama-Lube flowing freely so the engine does leave a trail of blue smoke where ever I have been.

Thirty plus years ago the smell of Yama-Lube was much more common than it is today. Back in the day there were both street bikes, and dirt bikes that were 2 strokes and used a constant flow of oil in their fuel to keep the engine well lubricated. Today, people will run down the street to stop you, only to point out that your engine is using oil and leaving a smoke trail.

There is no room in my garage for any EV other than my DeWalt cordless drill and my Quad-copter/Drone. The garage does have a ventilation system so I can powder coat parts as I desire without killing myself doing it.

 

A catalytic converter needs to be HOT in order to do its job. So, "No", the CAT won't eliminate all exhaust fumes at start-up. Your problem is one of poor air/fuel mixture during start-up. Sounds like a much too rich mixture to me. Most likely cause is that carb needs a good cleaning and rebuild. But choke adjustment could come into play, as well. Make as many adjustment changes as you can, FIRST. If that doesn't resolve the problem adequately, look into a carb rebuild.

 

Edit your title it makes no sense

 

I believe it's intended to be a fun way to get folks to read the message. I'm sure it caught a lot of us – likely you too – don't be sore, just chuckle and move on.

The best turn of the table is this from @Piersonpie

 

Everyone knows what he means 😂stinky cats