LUVTruck.com

Hi all, So my 79' failed the deq emissions test today, bummer.
The report shows that my CO levels are too high.
I was told by the guy at the station that this could be due to a variety of problems, but most likely timing or too rich of a fuel mixture.
What should I do?

Check what your timing is at now and see if it can be adjusted and you can also calibrate your carberator to have a not so rich fuel set up. I am still new on here and wih my LUv but I have spent a lot of time on here just reading everyone's troubles and the others answers. Lots of advice on here if you look for emissions advice in the search box

Here is the factory procedure: Check that the timing is set to 6 deg BTDC at engine idle. With the engine warmed up to operating temperature, adjust the idle (speed) screw to 900 rpm. With the (mixture) screw slowly turn it in or out to find the highest idle speed. Then reajust the speed down to 900 rpm again if necessary (speed screw). Go back and forth between the idle (speed) screw and the idle (mixture) screw until you get the smoothest best idle at 900 rpm. Then very slowly turn in the idle (mixture) screw until speed drops to 850 rpm. You should now pass smog test.

remember when adjusting carb settings or adjusting timing always make sure your vehicle is up to operating temperature and you disconnect the vacuum advance and plug it!!!!!!!! this is that weird looking space ship with a nipple attached to the distributor....

and remember when going to do emissions always make sure your vehicle is up to operating temperature!!!!!!


secondly make sure all emissions control devices are functional and with in spec (this is where owning a gm service manual come in handy)!!!!!! egr valve, air pump, ait pump lines also make sure all of your vacuum lines are in serviceable condition and not cracked or hard and connected CORRECTLY....

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Friends don't let friends drive stock...
76 mikado, emissions delete, dual alternator, rejetted 1.9 carb swap, non factory body lines
soon non points distributor, single (semi sealed beam) head light conversion

The factory procedures sticker located on the underside of the hood said to disconnect the vacuum lines from three different mechanisms. Off the top of my head I believe they were: The idle compensator, Distributor, and EGR Valve. All of which I successfully located, disconnected, and plugged after having gotten the truck up to operating temp. I then adjusted the idle mixture, and idle speed.

One question about the adjustments I made, I infer that these adjustments (idle mixture, idle speed) only hold true for when the truck is idling, hence idle speed and idle mixture. Or do the adjustments made apply to all ranges of speed? The DEQ station guy said that The increase in CO and Hydrocarbons heightened only when I brought my RPM's up to 2500, when I was idling I was fine.

since these have a vacuum/cintrifical advance they will hold ~true through the entire rev range (i think its 4* the the distributor advances under load and high rpm) secondly these are 2 barrel carbs so when you hit the higher rpm the secondary opens allowing for more fuel at higher rpm = ~same air fuel ratio

_________________
Friends don't let friends drive stock...
76 mikado, emissions delete, dual alternator, rejetted 1.9 carb swap, non factory body lines
soon non points distributor, single (semi sealed beam) head light conversion

If it passes idle ok but not at speed suspect the following: Air pump system not working, EGR valve not operating, bad catalitic converter (if california emissions and it has one) some do, some don't.