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post #1 of (permalink) Old 12-01-2005, 10:35 AM
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Project SBC Failed Smog - Smog Guru input?

So close, but no smog.

Failed HC at 25 MPH.
Here are the results
HC CO NO
15MPH Max 84 Meas 84 Max 0.57 Meas 0.06 Max 482 Meas 36
25MPH Max 49 Meas 69 Max 0.70 Meas 0.07 Max 735 Meas 35

The ref suggested I change plugs (I have platnums in it right now) and drive it on the Fwy.....that could be a problem....no windshield...much less any lights.

So....do I change plugs now and drive it around the block a few times, or do I just go ahead and get it painted and then drive it a few days.....

Engine has been sitting up for about 3-4 years....

What do you think smog guru's?
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post #2 of (permalink) Old 12-01-2005, 11:15 AM
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Re: Project SBC Failed Smog - Smog Guru input?

You are close!
It's just a teeny bit too lean. Retarding the timing a couple degrees might help.
It's lean enough that the flame goes out in the chamber a little too early, leaving a small amount of raw gas.

Richening the mixture screws slightly MIGHT help, but may cause you to fail at low speed.

If the gas has been in the tank a long time - change it. You might have to drain it or drive it a bit.

Change the plugs as recommended - plats are terrible in engines that weren't designed for them. Use STOCK plugs called out for that ENGINE, not the for ignition or anything else.
Set the gaps SLIGHTLY on the wide side. (The slightly wider gap ignites better at lower/mid range speeds. Not so good for high R's though.) Regap after you pass. The stock plugs - the ones the HEADS were designed around - have the correct reach and indexing - very important for emissions. The plats are too "one size fits all."

Then make sure the gas is no older than a week (the addatives they put in evaporate fast.)

And - the trick - that morning - add a pint of DENATURED ALCOHOL to the tank. Same stuff as the "garanteed to pass" stuff. Not rubbing alcohol, not Vodka (put that in you.) DENATURED ALCOHOL is available in hardware and paint stores - where they keep the laquer thinner. 99 cents or so.

Warm it up, make sure the alcohol has had a chance to mix in.

If it fails again at high speed, but CO at low speed is way lower than the cut point - try richening the idle mixture screws just a tad. That might be just enough to get by.

Good Luck.

BTW -- I think paint only helps if it's passionate pink with orange, green, and purple stripes - the ref passes it quickly so he doesn't have to keep looking at it!
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post #3 of (permalink) Old 12-01-2005, 12:10 PM
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Re: Project SBC Failed Smog - Smog Guru input?

Thanks Rich....I figured (and hoped) you would be one of the first to chim in....
The gas in the tank is about 1 1/2 years old.....do you think that might me an issue?????? LOL Never thought of that.

I'm going to go ahead and get it to the paint shop. My registration only expired 2 weeks ago....Once I get it back I can drive it for a few more weeks before I have an issue....reg is paid, just need the smog. DMV will be me a temp pass so I don't get a ticket......gota set a good example.....

I think I'll replace the plug wires as well. No idea how hold they are. It might be worthwhile putting a scope on it too.....my gut feeling is that my spark is breaking down under load......but based on what your telling me, everything makes sense now.
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post #4 of (permalink) Old 12-01-2005, 05:25 PM
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Re: Project SBC Failed Smog - Smog Guru input?

In about a month's time most all the addatives have evaporated. Best if it's less than 2 weeks old. Yes, it DOES make a difference. The addatives really help control emissions.

He He - the other day I was working on my motorhome - haven't run it for about 4 years. Couldn't get fuel pressure. Looked underneath - a rat or squirrel had eaten the fuel line - had a big puddle underneath. I was surprised I didn't smell it.
Put some on a rag - smelled it - it didn't even smell like gas, more like water.
Touched a match to a rag with some on it - it hardly burned at all!
Yesterday I started it on that old gas (had to "kick it" with propane at first) I'm surprised it ran at all - it ran pretty well - for "immitation water." I'd guess emissions are out of sight though. It'll take a couple tanks to burn out the old stuff.
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post #5 of (permalink) Old 12-01-2005, 06:59 PM
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Re: Project SBC Failed Smog - Smog Guru input?

All my old junk passes smog ... usually with the comment "that thing runs really clean"
I run the best gas I can for a few days before the test. And, like you say add about a pint to a quart of Methyl Hydrate(alcohol ...thats what they call it up here) to the tank.
Make sure it is good and warmed up when it gets to the test and it seems to work.

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post #6 of (permalink) Old 12-02-2005, 01:09 AM
 
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Re: Project SBC Failed Smog - Smog Guru input?

damn, i cnan't rember what a tbi 350's plugs are off hand, if i rember i'll post up at work tomorw what the delco # is. The factory plug nuber it's calling for may be a platunium but i highly dobut it perfroms like a stock delco.Bosch platinums could be yrou problem (mechanics hate em, auto zone sells a lot and i hear they are the root of most problems).
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post #7 of (permalink) Old 12-02-2005, 12:10 PM
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Re: Project SBC Failed Smog - Smog Guru input?

Make sure it's fully warmed up before trying again- and I mean warmed up. I have held my RPM's to 3500-4000 for about a min before getting sniffed- seems to make a difference. you can watch the numbers go up as the motor cools back down.
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post #8 of (permalink) Old 12-02-2005, 12:39 PM
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Re: Project SBC Failed Smog - Smog Guru input?

I'm pretty sure my problem is the 1 1/2 year old gas in the tank. There is a good chance the tank has water in it as well....we started seeing steam come out the pipe during the 25 MPH test.

When I get the jeep back from the paint shop...and get it all together, I'll drop the tank...clean it out real good (I may have a bad sender as well) and start with fresh gas.
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