Alright I know right off the bat there are going to be numerous that's ILLEGAL comments. So lets try this in theory! So not to stir the pot.
In theory! I'm curious if it is possible for a non CC Carb to pass a sniff test. No visual inspection none of that stuff being taken into account, just straight up numbers. Lets use a 350 with a mild magnum cam, 750 demon Carb, 305 heads short deck heads with 194/160 valves, headman Shorties block hugger headers with a 3 inch exhaust WITH high flow cat and muffler and stock rear end.
What tuning could be done to make it JUST PASS the sniff test by numbers?

 

A lot probably depends on where the sniff test is they passing numbers change from place to place.

 

Canada, Ontario

 

I don't know much about canada except they have awesome strippers. What are the limits where you are?

 

Well from this link http://www.ene.gov.on.ca/stdprodcons...rod_080001.pdf
All I could gather was 60 NC. 0.33 Co. And 675 nox. But to me those numbers don't sound right.

 

It will pass in the UK, as long as the car is 1992 and older.

 

Lol the UK is a bit aways away from Canada! Do you even see many third gens over there?

 

LOL yeah, suprisingly there is a huge following of them. Since my car is black, I get comments all the time "Is that the KITT car from knight rider?" I got tired of telling the difference (KITT was an 82, mine is an 84 GTA clone), so I just say "Yeah" and they're like "AWSOME!!" haha I"m part of the "Pontiac Owners club, UK" and we have 500 members. There are also 6 third gen cars that live within 20 miles of me, two fiero's and four older pontiacts, a 69 GTO, 67 Firebird, and 2 Bandit Cars.

 

That's awesome, but back on topic in theory! What tuning would be needed or is it even possible?

I actually got hold of an emission test for a 305. The limits are. CURB IDOL = Hc ppm 200. CO% 1.0. 38 km Test Limit = HC ppm 55 CO% 0.31 N0X 612

I guess those chart numbers weren't to off! Well does anyone know if said theory car is in the realm of possibility to achieve those numbers???????

 

It's been done. (yes, by me)

Is it repeatable? by someone else? a whole other question.

It'll be ALOT less unlikely if you have a cat and an intact AIR system.

 

Alright well It won't have an air system but It will have a cat. What did you do to pass tuning, timining, high test???

 

The carb would need to be dialed in, your timing set and the cat installed. If you do a search, there are people here that pass emissions with no AIR System, but they are also running TPI, not carbed. I would invest in an A/F meter and gauge and dial it in with that, once your mixture is right, that should be passing, or dang close if it's not.

 

I chimed in on this one...
https://www.thirdgen.org/forums/carb...-problems.html

He passed pretty easily. Lean out idle, get your timing where it needs to be (and that wont be 12 degrees advance at idle) and put a CAT on there. I think the concern will be NOx level. Higher compression combined with a lot of timing lead can bump up NOx.

 

I put a cat and AIR system on it, and tuned it.

Then you can pretty much fugheddaboutit. Either you want it to pass, in which case you'll do what it takes; or .... not. Pretty hard to alter chemistry by sheer willpower. (or: won'tpower?)

A cat works by combining free oxygen in the exh stream, with the various things it's supposed to control. Can't turn CO into CO2 without another O. Pretty simple stuff here.

If you just hook up the pump's entire output to the port in the side of the cat, that should do the trick.