Z28 Will not pass emisions test

Bubba38 · May 16, 2002

Recently purchased 69 RS/Z28 which has to go
thru emissions test 1 time. The car fails
HC test. Reading is 13.8838 grams per mile
limit is 7.0000. Orig. carb was rebuilt.
Car is all nos. matching & stock. I've been
told you have to advance the timing to get Z28's running ok, but then it fails testing.
Car also bogs down in 1st & hesitates when
going thru the gears.Car is in Wisconsin.

HOTROD69CAMARO · May 16, 2002

Are there any shops in your area that could give you some hints on how to get it to pass then tune the car for your liking after? First how long since it had a tune up. Plugs, points,air filter etc. Second, how about putting a couple hotter heat range plugs in it and adjust the mixture to the lean side just to get it to pass, I would think retarding the timing would help pass smog.

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Black 69 camaro

Silver69Camaro · May 16, 2002

There are a few gas additives that 'gaurantee' you to pass emissions. I have no idea if they work. Something to try anyway.

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1969 Base Camaro
Vortec 355, Perf. RPM, Demon Carb., TH-400
All sheetmetal is NOS GM
See my NEW webpage at: http://www.geocities.com/compuboy007/

Sleepy-69 · May 16, 2002

I don't know anything about Wisconsin emission laws, but it seems there'd be an exemption for 30+ year old hobby/antique cars.

Does WI nake a destinction between a brand new Caddy and a 60's Chevy?

[This message has been edited by Sleepy-69 (edited 05-16-2002).]

67 Prostreet · May 16, 2002

Bubba38, Making your car pass the test should be all that hard! If everything is still stock check the following items...

1.) Make sure that you have fresh plugs and that the ignition wires are in good shape!
Also check cap and rotor

2.) Adjust the ignition time backwards to lower you emisions output! (Try somewhere around 8-10 degrees)

3.) Lean the idle adjustment screws to the point where the car starts to stumble and turn them back just a hair.

You're right about the engine wanting more timing to run correctly, however you'll need to do the opposite to get through the test!

Our emissions program has changed for older cars (25 + years) old and you can get a collectors plate that only requires that you pass once

One thing that you may also check into is that the emissions program here had an exemption that required that you spent a determined amout attempting to make the car pass. If after the dollar amount was met or exceeded they would consider you exempt and allow you to plate the vehicle

Hope this helps

Tom

[This message has been edited by 67 Prostreet (edited 05-16-2002).]

sschevyfan · May 17, 2002

Hey neighbor! Make sure you have a decent thermostat in it so it's not running to cold.180 plus would be ideal.Hc emissions is raw unburned fuel.Make sure she's not misfiring.How old are the plug wires?What were the co numbers? High co is a rich mixture.This is a 'real' numbers matching 302 Z28?!

Milan · May 17, 2002

I thought HC was measured in Parts per million (ppm). When did that change?

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67 prostreet BB Camaro
71 BB SS Chevelle (clone)
2002 35th anniv SS Z28 conv.

Bubba38 · May 17, 2002

<BLOCKQUOTE>quote:</font><HR>Originally posted by sschevyfan:
Hey neighbor! Make sure you have a decent thermostat in it so it's not running to cold.180 plus would be ideal.Hc emissions is raw unburned fuel.Make sure she's not misfiring.How old are the plug wires?What were the co numbers? High co is a rich mixture.This is a 'real' numbers matching 302 Z28?! <HR></BLOCKQUOTE>

Bubba38 · May 17, 2002

<BLOCKQUOTE>quote:</font><HR>Originally posted by sschevyfan:
Hey neighbor! Make sure you have a decent thermostat in it so it's not running to cold.180 plus would be ideal.Hc emissions is raw unburned fuel.Make sure she's not misfiring.How old are the plug wires?What were the co numbers? High co is a rich mixture.This is a 'real' numbers matching 302 Z28?! <HR></BLOCKQUOTE> CO Nos. are 92.223.
Passing is 120.000 & Yes,an Orig. unrestored RS/Z28,Burgandy W/Wht.Vinyl top & Stripes.

William · May 18, 2002

Sounds like N633713...

sparky68 · May 18, 2002

This is from personal experience with similar problems. Beside the other advice posted here:
1. Make sure your valve train is in good shape & properly adjusted. You'll never pass if you have exhaust valves not seating right.

2. Change your oil, filter & PCV, even if you did it last week.

3. I was very disappointed with the other "emissions" additives. But Z-Max really works on several levels. Cleans out carbon deposits like crazy. So make sure your gaskets/seals are in good shape or after its done cleaning you'll have oil leaking from everywhere. I used both the oil and fuel additive and the car passed with numbers in the 25% of allowable range.

Bare in mind, I'm not saying my list is all inclusive. I did most of the other stuff these guys advized too!!!

Bubba38 · May 18, 2002

<BLOCKQUOTE>quote:</font><HR>Originally posted by William:
Sounds like N633713...<HR></BLOCKQUOTE>
William,
Thats the VIN.#. Do you know this Car?
If so, what can you tell me about it?

6869ssrs · May 19, 2002

Milan, most 4/5 gas anylizers measure in ppm, but the EPA measures auto emmisions in grams per mile during a i/m 240 emmisions test. Hope that answers your ?

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Don Christenson
68 ss/rs 350/powerglide
69 ss/rs 396/375 M22

Milan · May 20, 2002

Whew thanks I thought I needed to go back and learn a new gas analyzer. Man I totally forgot about that!! Guess I am rustier that I thought

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67 prostreet BB Camaro
71 BB SS Chevelle (clone)
2002 35th anniv SS Z28 conv.

Z28 Will not pass emisions test

Bubba38

HOTROD69CAMARO

Silver69Camaro

Sleepy-69

67 Prostreet

sschevyfan

Milan

Bubba38

Bubba38

William

sparky68

Bubba38

6869ssrs

Milan

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