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Need all input on my smog test results....please

J

jakeslim

1/2 ton status
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Ok, finally got the nerve to take my k5 down to the smog station.
Here are the specs:
- 383 engine(they don't know that of course)
- carb is new edelbrock(1 yr)
- intake is new (1 yr)
- original air filter unit
- no smoke at start up or after getting warm
- idles at 600 or close to it
- headers w/dual exhaust
- no cats (77 trucks no need)
- Federal emmissions truck (heavy duty)

Here are my test results.....yikes:
Pcv - "Pass"
Vacuum lines - "disconnect"
Ignition timing - "Pass"
Thermostatic Air Cleaner - "Modified"
Other related emis. components - "Modified"
Carburetor - "Pass"
Fuel Cap Visual - "Pass"

(They were easy and let me bypass the "rollers" which was great since the ratios would screw me ever worse!)
................Max-HC....HC(PPM)....Max-CO....CO(%)
At 760 rpm.......300......741........3.00......1.28 GP(failed)
At 2500 rpm.......350......74........3.50......1.21 PASS


Why is it miserable at 760? Is it my vacuum lines? I have the carb vacuumed to the intake port...is that the problem?

lets hear it...oh yeah, this is California of course.
One more thing, he said headers are cool but need to have a CARB#. So, now i need to buy some new headers. Hedman's 69831's have the A.I.R and are 50 state legal, BUT both the goons at Jegs and Summit did not know if these headers had the CARB# on them.....

Help.
 
If they're 50 state legal they will have to have a CARB number.

It looks to me as if your fuel mixture is too rich at idle.

Check your ignition timing as well before the re-test.

As to the visual stuff the Cali guys will have to help ya there.
 
thanks for the info on the headers Tim. Some hedman elite headers will look good in place of the old rusty ones!

So its basically my HC levels at low load(760rpm) that are too high. If the air/fuel was off at idle, wouldn't it be off at high rpms also(i passed there)?
 
No. The mixture is controlled by the jets and metering rods at high rpms and by the idle mixture screws at low rpms. Turning the idle mixture screws clockwise leans out the idle mixture.

I'm working on getting my '86 Jimmy to pass also. It has a 350 in it in place of the original 305 and only cats for emmission controls. I just rejetted the carb and put in new metering rods for 12% leaner mixture for the Denver altitude. I'm still getting sooty exhaust when I rev the engine and I even tried running it with the idle screws cranked all the way down. Not sure what the problem is. I did also find a vacuum leak and fixed it. It ran better, but still have the sooty exhaust.

I wonder if maybe the pipes, mufflers, and cats are so clogged up with that it's just still blowing through. Any ideas?
 
He gave me a list of things to fix....headers(carb#), vacuum hoses, "adjustments"(i figure he means air fuel)

Now of course he attached some repair fee estimates to items 2 and 3 above. I figure it may be in my best interest to pay him for item 3(adjustments @ $90). That way I am paying him to bring my HC levels down so that I can pass. It becomes his responsibility now to make sure I pass instead of me paying for a pretest to ensure I tuned it right.

The "modified" denotation was due to mis-routing of vacuum hoses. It was also because of the headers. I will be fixing both of these this week.
 
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I even tried running it with the idle screws cranked all the way down.

[/ QUOTE ]

Sounds like the reason your idle mixture is too rich is because you likely destroyed your idle mixture screws by cranking them all the way in. Your engine should hardly run, if at all with them screwed in all the way. It should be so lean that it should misfire at idle with them in that far.

I'd likely say that you're too rich across the board if you're getting sooty exhaust off idle and into your power circuits. I'd try jetting another stage or two leaner in the primary circuit. I doubt the emissions test will ever require you to get into the secondaries so you can probably leave those alone.
 
If you pay someone to fix it, this will (hopefully) be worthless information, but if your engine runs with the idle screws all the way in, the idle screw (the one that sets curb idle) is probably set too high, I'd speculate covering up the fact that the vacuum routing is a problem causing a vacuum leak, and/or timing is wrong.

At idle the carb is probably fueling the engine off of the primary "circuit" and not using the idle circuit as it should be.
 
Sorry, don't mean to hijack the topic. Here's what I have done. I only turned the idle screws all the way in because I had tried about everything else to no avail. I only turned them in until they touched gently so I don't think I would have damaged them. That's not to say they weren't already damaged though. Since that didn't help I put them back to lean-best-idle setting. I don't have a timing light so this is sure to be not optimal but I tested it at both retarded and advanced extremes and it didn't make any difference. All vacuum lines are fine.

The carb is an edelbrock 1405 and I've replaced all four jets and the metering rods with the leanest they sell, 12%.

It also has new plugs and wires and it's running pretty good now otherwise. I took it out and ran it and heated it up. When I pulled back in drive and goosed gas there was no sooty black smoke. I shut it off and restarted it and there was some, I then let it idle for a few seconds and then goosed it again. There was a hesitation in throttle response like it it had to clear its throat and it spit out black smoke again. Revving it up for a bit seems to clean it up some. When idling though it seems to load up with gas.

I'm at a loss. Thinking of trying to lower the floats and see what that does. I might try replacing the carb too. That seems to be where the problem is, but I'm not absolutely certain of it.

Thanks for advice.
 
They don't even lift the hood here. /forums/images/graemlins/laugh.gif
Just toss an inductor on the hood to catch RPM, Anal probe and visual on the cat. /forums/images/graemlins/grin.gif

My 454 3/4 ton 88 Suburban is exempt because it has a 8600lb GVWR. /forums/images/graemlins/rotfl.gif
 
[ QUOTE ]
The carb is an edelbrock 1405 and I've replaced all four jets and the metering rods with the leanest they sell, 12%.

[/ QUOTE ]

You can go leaner. They just won't list them in the chart in your manual because they don't think you need to go that far.

You're still too rich.

Keep going you'll get there.

And set your timing with a light, eliminating potential ignition issues is the only way to ensure that you won't go too lean and have a knock prone engine.
 
Well its running rich at idle, as said above, so you need to adjust the carb, but that doesnt really matter, because even if your tail pipe readings pass, your gonna fail for not passing the visual.
 
[ QUOTE ]
Well its running rich at idle, as said above, so you need to adjust the carb, but that doesnt really matter, because even if your tail pipe readings pass, your gonna fail for not passing the visual.

[/ QUOTE ]

Yeah, I'll get it to idle correctly no problem, and the vacuum lines are no biggy. I have been researching and the "MODIFIED" selection is ok but the parts have to replace the original parts and have a C.A.R.B. # (E.O. #)

I went on to California smog site and found a HUGE list of aftermarket parts that are LEGAL in CA including a ton of long tube headers etc. Pretty cool actually. I am ordering some new headers today and that will take care of all my "fails". I will most likely tune the carb my self and pay for a "pretest" so that I don't fail again and get sent to the State. CA test automatically send the results to the DMV...its crazy.
 
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