Hey,

I recently removed the exhaust system on my truck from behind the cab on back. I noticed that it had no hangers on it what so ever. It was all just hanging from the exhaust manifolds. While underneath the truck, hacking away at the pipe, I noticed that it doesn't have a catalytic converter. Did '81 F100s not come with a cat. or is mine missing? Also, since this engine is a replacement, maybe that year of engine didn't require a cat. converter.

Anyway, I've heard that if there never was a cat. converter on the truck when it came from the factory, you can run straight pipes. Is this true? If so, I'd really like to eliminate the Y-pipe and run straight pipes off each manifold.
If I do this, what will I need to do to make sure I have the correct back pressure? I am asking this because right now my truck seems to be a little more sluggish than it did before I removed the exhaust pipe.
Thanks in advance!

 

Quote:

Originally Posted by Explorer Freak

I noticed that it had no hangers on it what so ever. It was all just hanging from the exhaust manifolds.

You can get generic exhaust hangers pretty cheap at an auto parts store.

Quote:

Originally Posted by Explorer Freak

Did '81 F100s not come with a cat. or is mine missing? Also, since this engine is a replacement, maybe that year of engine didn't require a cat. converter.

Yours is likely missing; it is the vehicle that determines the need for a cat, not
the engine. Look on your radiator support (also sometimes on an engine valve
cover) , you should have a well-affixed sticker that will say CATALYST or
NON-CATALYST; here's mine:

Quote:

Originally Posted by Explorer Freak

I've heard that if there never was a cat. converter on the truck when it came from the factory, you can run straight pipes. Is this true?

Check your local laws.

Quote:

Originally Posted by Explorer Freak

If I do this, what will I need to do to make sure I have the correct back pressure?

Ensure the diameter of your exhaust system pipes is correct.

 

Thanks!

I was also thinking about making it true duals with Cherry Bombs just to make sure I'm legal.

 

DUAL EXHAUST CONVERSION KITS - JCWhitney

true dual with glass pack mufflers (sorry i thought we were talking about mufflers not cats woops.) lol
it's the set i'm going to be getting..
car-sound.com has hi flow cats that make your exhaust sound like there's no cat on em

 

'81 F100's definitely came with a cat, F150 that year might not have, but the F100 was certainly under the GVWR requiring it.

 

My 81 had the cat orginally on it. That is until i removed it and the muffler.

Im currently running straight pipe duals clear from the manifolds. I just redid my whole exhaust several weeks ago. An i love it. Very loud, yet a great tone since its got a v8.

Just go to your local auto store and pick up 3 or 4 hangers to hold your exhaust. They will cost 4-5 dollars each or so.

If i were you id just check your local laws and find how strict your cops are around there. If they seem cool id say just keep the muffler and cat off it. Round here you could prob run around with the no pipes at all, just runnning off the manifolds! I say this because i've done it twice now, and i honestly hate it hahaha. So so so so loud, and annoying in the cab haha.

I'm not sure of the engine in your truck, but i have the 302. If your wanting a sound clip of the 302 with just pipes i can make one just let me know.

 

If there is no sticker, I'm pretty-sure the VIN shows if it was originally equipped with a cat. Emissions people go by the VIN. My '81 is cat equipped.

 

All F-100s from 1975 to 1983 had catalytic converters.

All F-150s were required to have catalytic converters by 1983, and some F-150s depending on their GVWR had them from 1978.

The F-150 was introduced in 1975 to get around the smog control laws of the time. When the F-150 had the same smog restrictions as the F-100 by 1983. There was no longer a reason to have two classes of half ton pickup, so the F-100 was dropped.

This little game of trying to get around the smog control and fuel economy restrictions laws still happens today. Why a new 2010 F-150 can haul 10,000 GVWR or better. The same as a 1980's F-350.

 

I know I've heard somewhere that if the engine in the vehicle is from a year before cat. converters, you don't need to run one, regardless of the year of the truck it's in.

Anyway, after reading your responses, I think I'm going to leave the cat off, but put glass packs on to keep the cops happy. If I run off each manifold separatly, it will run me around $80-100 (glass packs, pipes, exhaust hangers/clamps). If I just leave it with one pipe it will be around $50-60.

I also want headers, but that will be for another time, when I have more money.

 

Check your local laws, what I stated is how it works in Colorado.

 

If going by the strict sense of the law. Federal law states that you cannot remove smog equipment from any vehicle unless it's faulty or needs replacement. After 25 or 30 years or so, replacement parts are almost non existant so taking it off and leaving it off is shown a blind eye in most states.

In California it goes a few steps further. You cannot remove the smog control equipment unless it's faulty, and you have to replace it with CARB approved equipment. If the parts are not avaliable, you have to get them from the wrecker, or have them specially made and CARB approved, or scrap the vehicle.

In California, you are not allowed to use an older engine than the model year of the vehicle. If you use a newer engine, the smog devices have to be the same year as the engine. To put a 1994 engine in a 1981, you need 1994 smog equipment. You cannot put a 1980 engine in a 1981 at all.

No vehicles are smog exempt in California. 1975 and older right now are only Smog Test exempt, which is different. They are still required by law to retain the same smog parts and to have them working properly. Why people with 1975 and older vehicles are worried if California rolls back the smog test exemption back to 1965 or 1960 like they want.

So the point is, by the letter of the law, you are supposed to replace the defective equipment if possible. But each state enforces that federal law differently and has their own laws on top of the federal ones. California being the strictest in the nation.

Check with your local laws. Also if you plan on moving to California, and want to keep your truck, it must have it's original equipment in working order. The wrecking yards are full of out of state vehicles, and vehicles that wont pass smog tests.

 

I know a lot could change in a year.My 82 F150 Supercab 302 carbed engine has the word "Catalyst" on the sticker you speak of.
Someone has removed them and added duels with Cherry Bombs.
I love the sound.
Supposidely I am the second owner.???