1969 350 Emissions Inspection Problem

[Doms86C10]

Hey everyone I never post on here but always read and I hope this can give me some clarity on what needs to be done for my truck to pass inspection. The truck itself is a 2WD 1986 C10 shortbed. More importantly the engine is a 1969 2 bolt main 350 SBC bored out .030 edelbrock intake, holley 650 cfm carb, long tube headers, true dual exhaust with catalytic convertors and flowmasters. In NJ i'm not sure how it's set up but the 1969 engine has to pass 1986 350 TBI emissions standards which is under 220 HC, and under 1.2% CO. The engine is freshly tuned up and has a recent oil change, spark plugs have under 1,000 miles on them.

on 12/21/12 I went and did nothing special running 87 octane gas and getting the engine up to nice operating temperature and this is the reading I got

IDLE:
HC ppm: STANDARD-220 READING-147
CO%: STANDARD-1.20 READING-3.25

HIGH IDLE:
HC ppm: STANDARD-220 READING-71
CO%: STANDARD-1.20 READING-2.42

on 1/02/12 I went back again this time I adjusted the carb with a vacuum gauge to produce maximum vacuum, let the engine warm up to around 200 degrees again, put the CRC gauranteed to pass autozone stuff through the tank and filled back up with 87 octance. this time I retarded the timing on the engine before I ran it through.

IDLE:
HC ppm: STANDARD-220 READING-138
CO%: STANDARD-1.20 READING-1.89

HIGH IDLE:
HC ppm: STANDARD-220 READING-81
CO%: STANDARD-1.20 READING-1.33

1/03/12 I went back because i felt the last time I was so close if I could just get lucky maybe it'll pass. This was the readings i didn't change anything from the last time and only drove it 20 miles but let it warm up again.

IDLE:
HC ppm: STANDARD-220 READING-182
CO%: STANDARD-1.20 READING-3.00

HIGH IDLE:
HC ppm: STANDARD-220 READING-64
CO%: STANDARD-1.20 READING-1.75

I read online that denatured alcohol will burn cleanly and if you put some in your tank when it is low it will help lower emissions. I ran my tank down to I'd say around 4 gallons. I dumped 1/2 a gallon of denatured alcohol and let it warm up to around 200 degrees again. this time i did not retard the timing but the engine was plenty hot as it was. this was the reading.

IDLE:
HC ppm: STANDARD-220 READING-145
CO%: STANDARD-1.20 READING-2.43

HIGH IDLE:
HC ppm: STANDARD-220 READING-78
CO%: STANDARD-1.20 READING-1.67

Now idk I can't find any other tips or tricks. If the engine has basically no emissions parts attached i.e. the charcoal filter or EGR. I tried retarding the timing, tune-up, CRC garaunteed to pass autozone stuff, tuning the carb with a vacuum gauge, Denatured alcohol 1/2 gallon to 4-5 gallons ratio. I think tomorrow i am going to dump the other half gallon into the tank and bring it up again. I see some people on forums swear by the stuff but so far I haven't seen any results and I am out of ideas. Any tips, tricks, or info would be appreciated and again I live in NJ. The truck can be insured under classic which doesnt require inspection but they give you a fuss if you park it outside and daily drive it and so on.

 

[89Suburban]

I am in the same boat with you in relations to the ******** emissions on these older trucks over here in PA. I feel your pain, and mine is a 89 TBI with all the emmisions **** hooked up from factory and I still get my balls busted trying to get it to pass.

 

[8T6K5]

Found online:

CO Failures (vehicles with carbs)

1. Engine not at operating temperature. Example, engine/cat cooled off while waiting in test line or has a stuck open or missing t-stat.

2. Bad or misadjusted float level.

3. Plugged air bleed passages or misadjusted main metering system, leaking fuel passages or gaskets.

4. Maladjusted idle air/fuel mixture screws.

5. Ruptured or sticking canister purge valve.

6. PCV plugged or drawing in fuel contaminated oil vapors.

7. Malfunctioning mixture control device.

8. Malfunctioning computer inputs. Example: O2 sensor defective, reading lean all the time. MAP sensor vacuum hose being clogged or broken (reading a heavy load all the time). Coolant temperature sensor having high resistance or open circuit (reading "cold engine" all the time). Throttle position sensor stuck or open ground, (reading wide open throttle).

9. Contaminated, restricted or bad catalytic converter.

 

[Jims86]

You should have them confirm those requirements. 86 Did not have TBI....at worst, it had a computer controlled q jet.
You can try to clean the cats with about a gallon of laquer thiner per 1/2 tank, or cut them off, and soak them in a tub of dawn and water for a couple of days. Make sure you have a 195* thermostat.
Another thing to consider is air injection and smog pump, those systems help keep the cats lit.
Make sure the exhaust crossover passages are clear in the manifold, thats another thing that helps keep fuel in suspension, instead of puddling in the manifold.
one more thing to consider, especially in an emissions testing situation where all they do is test emissions, and dont do a visual. It has been popular belief for a long time, that if there is no visual inspection,

"I can remove this or that, because "I think emissions are stupid" or " my grand daddy said I dont need it"


If you can afford to do so, and dyno tuning services are available where you are, I would suggest doing so. they tune your carb for best performance, along with ignition tuning, which also makes it more efficient....which translates into giving you a better shot at passing smog.