AZ Emissions

[JakeinAZ]

My 74 Series III has now failed the hydrocarbons at idle test 4 times. I got 1800 ppm, the limit is 400. I have checked the plugs, wires, airfilter, vaccuum lines, leaned it out and adjusted the timing. The timing was the one thing I was not the best at but I did it by the book. Is there anything else I can look at. Right now I can't drive it without passing emissions and I'd like to not have to take it to a "shop" unless anyone knows a good shop in Pheonix, AZ.

Thanks for your time.

Jake Barry

[greenmeanie]

Ok Jake,
Give us some details on your truck set up. Carb, dizzy, points or electronic ignition etc.

Secondly, tell me where you are in the valley. I'm way down on the south side and can give you the name of a place to go with reasonable rates. My 101 does her emissions each August so I prefer just to pay these people to sweat over a hot engine in 115° as it can be a bit of a battle.

High hydrocarbons indicates a miss. Contrary to the obvious thoughts you are probably running just a little too lean. I would turn up the fuel just a bit and then go back through the tuning process. You also need to make sure she is getting enough air and a good strong spark at the right time.

#1 Have you checked the valve clearances?
#2 For high HC retard your timing a bit which will help.
#3 Clean up or replace the dizzy cap and rotor.
#4 If you haven't done so already swap to an electronic ignition as it will give more precise spark control and is far less hassle and maintenance than points.

Timing is fairly easy. Pull the vaccuum line to the dizzy and clamp it. so you don't have an air leak in the carb. Set the idle speed which for a SIII with emissions equipment should be 825rpm. Loosen the dizy so that it rotates with a bit of resistance and turn until the desired marks match up. Tighten the dizzy down and reattach the vaccumm line.

Cheers
Gregor

[JakeinAZ]

Reply

I live out in Gilbert, so if you know of a place that would be great. The carb is a weber and the distibutor and rotor are about 4 years old. I haven't done #1 or #4 but it may be my next move. I had been passing no problems for the last 4 years and then this year it was sky high.

[greenmeanie]

Do the valves first. It's a no cost job and it is part of the scheduled maintenance for this engine. If you haven't done it in the last 6K miles it needs looking at.

I go to the emissions station off Chandler over by the I10. There is a place right next door that specialises in emissions called Chandler Automotive. They are behind the car wash. If they can put my 101 through your SIII wil be easy. They have mechanics that can still work on carbs which seems to be turning into a rare skill in this town.

I'm sure someone will disagree but in my opinion replacing the points with electronic ignition is one of the single best upgrades to your engine. I also like to use Magnecor leads instead of the LR ones.

Cheers
Gregor

[thixon]

"#1 Have you checked the valve clearances?
#2 For high HC retard your timing a bit which will help.
#3 Clean up or replace the dizzy cap and rotor.
#4 If you haven't done so already swap to an electronic ignition as it will give more precise spark control and is far less hassle and maintenance than points."


I'm betting on a combo of #1 and old points/bad timing. As Gregor said, swap to the electronic ignition. The only possible downside you could mention (and it would only be mentioned by an old school points fan) is that if the spark box fails on the trail, you're screwed. That is unless you have another, or you carry the original point/condensor with you and re-install it.

High, HC's can indicate a miss as Gregor said, but more to the point indicate an excess of fuel in the exhaust. Unburned fuel in the exhaust can be caused by improperly adjusted valves, the wrong timing, faulty ignition, vacuum leaks, worn out rings, or a bad plug/plugs, etc.

Cheers
Gregor[/quote]

[pvkd]

No body mentioned setting the dwell angle to 57 degrees?