Hey guys, well finally got around to taking my 85 firebird with the 327 from a 65 vette (all race parts but mild cam) to a Massachusetts emmisions test. Well it passes the safety and it even passed the NOx test real well. Probally due to a brand new Race cat. However it failed the CO and HC test misriably. With 3 time the limit for CO and twice the limit for HC Now I know my carb is running real rich so thats part of it. Other than the Cat it has no emmissions what so ever. I know a guy who had the old style mass emmisions tester where the car is at idle and he adjusted the carb so that it now passes that test but the new style test has the car on a dyno and makes the car have to pass at 40 miles an hour. He told me it probally wont pass that test. He said I need an AIR system. My question is about that. From what I understand and I may be wrong but doesn't the air pump only work at idle and then shuts off at any speed? If this is true and my car passes at idle how would this help? Or is the guy just not knowing what he is talking about? I also gave the guy my jet and rod set for my carb but I don't think he used any of them, just adjusted the screws, because they all still look new. So do any of you think it will pass the 40 mph test as is? Will putting in smaller jets and bigger rods and leaning it out any will help? I think I have a .092 jet and a .0705 1st step and .0475 2nd step rod for a total opening of .0215 About how small should I make the total opening to pass? My spark plugs are somewhat carbon fouled light coating of black, and the exhaust still smells rich. Also is the any tricks to help pass as well. I have heard some but not sure if they are true or will help with this particular test. One I heard is to make a small vaccum leak and another I heard was to run your tank dry and then put a couple of bottles of dry gas enough to run the test on. Do any of these work and do any of you know any other tricks? And lastly I was looking at a mod that I might like. Its a holley 4Di fuel injection system. All it is, is a 4 barrel carb with 4 fuel injectors that has a programmable computer with 5 ignition maps and a fuel map (or the other way around I can't remember)to choose from. Will this make it pass? Is fuel injection even cleaner running than a carb. It may be $1300 but it will still be cheaper than getting an air system since I would have to totally redo the exhaust pulles brackets and but the system. Plus that will take horsepower while the fuel injection will add. Thanks for any help you guys can give. I got 60 days to pass this. Sorry its so long though. Thanks again... Erik

 

heh I know how you feel. My car was failing HC, but I finally got a waiver today after spending 450 bucks. Try disconnecting a vaccum line to lean the mixture out, I know this guy with a carbed vette and this helped him pass.

 

327 - Nice engine, man, my father longs for the old 327 he had all the time, said it was the best runnin' Chevy he ever had.

Now down to business, I can tell you your NOx was low since you were running too rich (which cools the combustion chamber in a similar way that EGR does), which you already knew, and this is also the reason your CO and HC are high. NOx is most easily lowered by running rich or very lean, therefore if you passed the NOx by a significant difference, your best bet is to lean it out until you just pass on NOx. In most situations, your CO and HC emissions are inversely related to NOx levels. Once you understand what you are trying to control it becomes easier to come up with ideas.

But you don't want to lean it out until you get lean misfire, ideally you want to make the mixture stoichiometric or just slightly lean. Most catalytic converters provide the happiest medium of minimizing all three major emissions at the stoichiometric A/F ratio, however, you can lean it out a little past that to reduce CO and HC even further. When I say a little I mean less than 15.5:1 or so, or your NOx levels may not pass.

Now the way you go about tuning the mixture properly is by shelling out $150 and buying an air/fuel ratio monitor, which is just an oxygen sensor to weld into your exhaust system and a display to tell you whether you're lean or rich. Then you can experiment with jetting the carb until you get it where it will most likely pass the test.

The more expensive route, like you said, is to go with a fuel injection system although I don't think this is necessary if you have the carb jetted right and get good fuel atomization. I would try the cheapest route first, and if your cats are good you will probably get by. Hope this helps.

 

The cat is supposed to reduce HC and CO emissions; it has no effect on NOx.

IMHO, having fought this for many years, readings of 3 times and 2 times the limit for an 85 car with a 65 engine is not "failed miserably". The 65 motor as it came from the factory probably had about 6 times the emissions that the standard for 85s will allow. So, it may look terribly, but it's not as bleak as it sounds.

Start at the carb. Lean it out at part-throttle as far as it will go and not start surging, with rods & jets as you suggest. Lean the idle screws down ¼ turn below peak vacuum. ALl that a vacuum leak will do is add some extra air to the charge, which is the same thing as reducing the fuel, except that its greatest effect will be at idle. And, a "small" vacuum leak is basically negligible at any engine speed above idle, so it won't affect 40 MPH cruise conditions.

AIR is easy to put on, if your exhaust has the ports. Just go to the boneyard and strip one. It will definitely help.

FYI, I have a 400 with a Comp XR282HR and a Holley 800 CFM 4-barrel carb; in TN, they check it at idle,no visual at all, it passed easily with a good cat and functioning AIR. I have TES exhaust with AIR fittings, with the pump just hooked up full blast into the headers with no "air mgmt valve".

A TES at $300-something and $100 worth of crap from the scrap yard is a whole lot cheaper than a FI system.

The "dry gas" thing does in fact work. In fact, a cheaper way to accomplish the identical same thing, is to run it nearly dry and pour in a gallon of denatured alcohol from the hardware store; then if necessary add gasoline until it will run well enough to drive to the tester.

Good luck!

------------------
"So many Mustangs, so little time..."
ICON Motorsports

 

RB - The three-way catalyst's name is derived from the fact that it uses a combination of platinum, palladium and rhodium in a catalyst formulation to reduce all three major emissions components, including NOx. It is the focal point of a modern emissions control system, and can be 90% efficient. His may just be an oxidizing catalyst, however, in which case you are correct. Good idea on the AIR system too, it can't hurt.

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1990 IROC 350
Mods: Too busy trying to make it run right to mod it.
Airfoil, Dynomax cat-back, Accel coil, 180 t-stat, Bald Eagle tires
Hypertech fan switch, hot wife, new oil filter, thick rubber floormats.
18.0 @ 85MPH since I'm one big-a$$ MF
"It's better to have and not need than to need and not have."

 

Just had a recent test on my 86 TA. It had the factory 305 LG4 5 speed. I told the testers it had a 350, because i was missing some emissions equipment. This classifies it as a Hot Rod and, it gets tested under different rules. Anyways, my first test was terrible. HC were 260ppm with 108 allowed. CO was 4.7 with 0.60 allowed! NOx levels passed here as well. Our tests are the dyno ones at 40mph as well.

My major problems were fairly small ones. First, the choke was sticking open just a small amount. I wired it full open. I increased the timing from 4 degrees to 12. Finally, and i think this is what helped the most to be honest, i dumped 3/4 gallon of NAPTHA fuel (Coleman Stove/Camping Fuel) and 1 quart of Gas Line Antifreeze. NAPTHA fuel burns much cleaner than gas, and if you look at most fuel treatments, they contain NAPTHA. I heard that Gas Line Antifreeze that contains ISOPROTHOL (or something like that) helps lower tailpipe emissions as well.

Next test i passed. HC were 108 (just past) and CO levels were .06! Quite a change from 4.7.

Anyways, hope this helps some

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Current
86 TA 305 5 speed, hardtop
81 Z28 350, 4 speed, t-roof
99 Ducati 750 Super Sport

Former
85 Z28
94 TA

 

your best bet is to find a corrupt inspector.
In NY the inspectors try to fail you in order to get you to come back. I got to the point that I dont even bother to do it legaly no more.

 

well being from mass i tell you you wont have any luck find a easy fix for it , see we adobted the california emissons so its even harder to pass in MA now , and trying to buy a sticker is like trying to find bigfoot. What i do when it comes time for emmissions is i fill it with dry gas , and i mean fill it i run it till about a quarter of a tank then i buy a case of dry gas , and fill the tank , car should burn super clean from the alcohal , , well if you can get it to pass this year next year all you have to do is pass safety.

 

If you want to go with the alcohol/drygas route, you can save a few bucks by using rubbing alcohol instead. It's the same stuff as most brands of drygas and it's about 1/3 as expensive. The white gas or naphtha idea looks better to me because the alcohol strips oil off of just about anything it contacts like cylinder walls, valve stems, etc... If you use alcohol synthetic oil is a good idea

 

With your HC and CO so high, I doubt the carb was adjusted to full potential. You should be able to reach a point through carb tuning to get a very low CO and a spiked high HC reading. If your CR is not too high, you can also swap out to a step or two hotter plug to help your CO. List the setup and also check your airfilter and it's positioning for restrictions. Also see how far you can advance the timing and see if that helps a bit.

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"Pray to God, but at the same time use your hands"

-Greek Proverb

 

Sounds exactly like the problem i just got over last week trying to make my '84 with a carb'd 350 pass a dyno smog test. Just like you, I was high on both HC and CO%. I don't have my series of test results with me right now, but can let you know how it changed with different changes I made once I get them tomorrow. Anyways, my car did eventually pass. This is with no computer, no EGR, no AIR system (heddman shorty headers), and 625 cfm Carter carb. I tried leaning my carb and got it very close to passing (HC were good and CO% was only 1% or less away), but couldn't get it any better than that on my own. Here is what it actually took to pass:

-one rod size leaner
-new vac. advance can on my dist.
(I wasn't getting enough advance under load)

Here are a few places that might help you out:

http://www.recarbco.com/technical/index.html
http://home.fuse.net/rmsi/sniffer.html
http://www.users.bigpond.com/ergoff/Faq4.htm

as far as the catalytic converter goes, i've read conflicting things about whether it reduces NOx or CO and HC. And if I remember right, EGR reduces NOx (this may have been stated or proved wrong earlier, but i forgot some of the things from the thread).

Sorry for the length.
Good luck

 

Hey thanks guys, you given me many things to try so now I do have a place to start. As recommend I just bought from summit a lean/rich guage with O2 sensor so I have a base to adjust my carb right. Maybe this alone will get it to pass. But just in case I will try the dry gas/denatured alcohol too. The air system is kinda too expesive since I would need to buy a pump, all the tubes brackets pullies belts new cat and new manifolds and y-pipe since I had to have a custom made pipe for the particular ram horn style manifold I have. Well I hope it passes after all this. I think next time I will just buy my sticker instead of going through this again. As for the engine here is the list of parts and mods: 327 ci bored .040 over CR ratio between 9:1 and 10:1 (must run at least 92 octane) small journal crank trickflow 23 degree aluminum heads 2.02 1.6 valves roller rockers weiand stealth aluminum intake 600 CFM carter Manual choke carb with 1 inch phenolic spacer Edelbrock 1000 CFM triangle style filter accel super coil MSD 6A ignition box and mallory unilite mechanical advance distubtor. Ok I have already swaped the 160 degree thermostat for a 180 to get it to run hotter so I think that has helped a little (did it before the test) The air filter can't be positioned wrong since it is the edelbrock one. I have the distubtor advanced 12 degrees I spent like an hour trying to get it just right by the sound. It also has 34 degrees total advance. 36 is supposed to be max for a small block. Its mechanical advance so I cant have a vaccum prob with it. I have the AC delco rapid fire sprak plugs (not the splitfire) Number 5 which were recommend by the heads manufactor. Its a long plug and I don't think they are made any hotter. During the test I notice my choke was pulled half way out maybe if I leave full open it will do better. Just have problems idleing with full open in the cold winter. Maybe thats because its not adjusted and jeted right. If I get the perfect 14.7:1 mixture will I only need the chock to start and warm it up in the cold instead of using it while driving in the cold? Also can anyone conferm that the air pump only works at idle and shuts itself off at higher speeds. If so then I know it wont help with the 40 MPH test since mine already passes at idle just not at speed. Hey here is an idea since the inspection place can't test an AWD vechile since they only have a 1 axle dyno, do you think they will believe I mod'd my firebird this way?? LOL Oh well can't hurt if you go to a place with stupid inspectors. To bad mass requires you to go back to the same inspection station you failed at. The were hard the day I went and the were supposed to be easy! Thanks for all the help guys. If anyone else knows any other tricks let me know ok..... Erik

[This message has been edited by 327 firebird (edited March 16, 2001).]