Author Topic: Failed smog after distributor was rebuilt and timing set  (Read 564 times)

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Offline jvmagic

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Failed smog after distributor was rebuilt and timing set
« on: February 10, 2020, 07:16:41 PM »
Hi,

My 79' (403 olds) passed the smog check with flying colors back in 2017 after a tune-up and getting the car rebuilt by a local shop.  I probably drove the car 1k miles from Dec 17' to Dec 19'. 
I had the distributor rebuilt (probably didn't need it but I didn't think it would hurt) and had the timing advanced by an 'expert' with a "Sun" machine. 
The dizzy was installed and I set the timing to 18 (total advance set to 36 by 3k RPM).  I was told to connect to "port" instead of "manifold" which I did.  The car idles smoother and seems to run a tad cooler with some smoother acceleration as well.

I took the car for a smog chekc and it failed........NOX too high (2199).

HC - 34
CO - 0.01
CO2 - 12.20
O2 - 3.94
RPM - 0
NOX - 2199 (should be <800)

Before the dizzy was rebuilt and total advance set:
HC - 52
CO - 0.01   
CO2 - 5.7
O2 -  5.7
RPM - 1398
NOX - 233

I was told by the dizzy expert to retard the distributor and turn up the idle a little bit so I can pass smog once again.

Does this sound about right after a setting total advance on a 403 olds motor?


« Last Edit: February 10, 2020, 07:21:33 PM by jvmagic »

Offline Stringer

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Re: Failed smog after distributor was rebuilt and timing set
« Reply #1 on: February 10, 2020, 09:16:22 PM »
Best bet is to adjust it to stock; 1.5 - 2 turns out on the carb idle screws (or highest vacuum on a vacuum gage) and timing set to 180 @ 1100 rpm with the vacuum advance disconnected and the vacuum line plugged when making the adjustment.

That said....it has been my experience...unless you have a 5 gas analyzer, you are just taking a stab in the dark on carb and timing setting for passing emission. Many states have emission waivers - does yours?  I know for Arizona, where I reside, all you need is prof of "classic car" insurance at the time of registration renewal and just like that, you never have to worry about passing emissions again. I haven't had to worry about it for the last couple years.

Hope you get it worked out.
« Last Edit: February 10, 2020, 10:25:20 PM by Stringer »

Offline jvmagic

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Re: Failed smog after distributor was rebuilt and timing set
« Reply #2 on: February 11, 2020, 12:36:07 PM »
Best bet is to adjust it to stock; 1.5 - 2 turns out on the carb idle screws (or highest vacuum on a vacuum gage) and timing set to 180 @ 1100 rpm with the vacuum advance disconnected and the vacuum line plugged when making the adjustment.

That said....it has been my experience...unless you have a 5 gas analyzer, you are just taking a stab in the dark on carb and timing setting for passing emission. Many states have emission waivers - does yours?  I know for Arizona, where I reside, all you need is prof of "classic car" insurance at the time of registration renewal and just like that, you never have to worry about passing emissions again. I haven't had to worry about it for the last couple years.

Hope you get it worked out.

I'm in CA so I don't think I have this option available.  Thanks!

Offline Stringer

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Re: Failed smog after distributor was rebuilt and timing set
« Reply #3 on: February 11, 2020, 07:48:37 PM »
Sorry to hear about the restrictions. If I was in your position I would purchase a gas analyser.  When I was trying to keep my 79 passing emissions I would literally have to give the car a tune up every year, make some adjustments, and usually have to go the the emission testing station 2-3 times before it would pass.  3 years ago I had the heads redone and I couldn't get it to pass. It would pass at idle but fail under load...it was then that got the waiver.  I wish I would have done it earlier.

If I were required to make those adjustments today, I would get a gas analyser.  That way I could make the adjustments and have instant feed back. Emissions testing is also something that you will have to deal with regularly so the expense of the machine would be worth it (at least to me it would be).
« Last Edit: February 12, 2020, 11:13:32 PM by Stringer »