Failed the emissions test today, the HC readings were just a bit too high? What are the most likely culprits? Haven't checked timing or anything, will try tonight. I tried to run it pretty good before the test, but it doesn't like to warm up much! Also, the Cat convertor and O2 sensor look to be real new and the motor runs real nice and smooth with no visible smoke.

Thanks for the help!

Bill C.

Twice, I’ve just changed the cat out and HC dropped during a retest.

be sure to check the timing, that can change it a lot if it is way advanced and make sure the idle speed is correct.

This might sound like a dumb question, but why would you have a emissions test done on a 1971?
Aren't cars made before 1974 exempt?

Regards,

Steve Haraway
1971 SS396

Change the oil and get the water temp up to at least 180*.

Originally posted by USFATL:
This might sound like a dumb question, but why would you have a emissions test done on a 1971?
Aren't cars made before 1974 exempt?

Regards,

Steve Haraway
1971 SS396 different states have different laws

I'm guessing Bill's not smogging his 71. That has no cat and sensor. Probably some tricked out Dodge racing van or something.

Ouch John... A MOPAR??!! NEVER!!

But yes, Steve, you caught me... it is on my tow vehicle... a 90 Suburban! It has a new cat convertor and O2 sensor and a non-adjustable idle speed circuit. I'll check the timing and report back!!

Bill C.

Update: I just checked the timing and here's what it looked(s) like. With everything hooked up, the timing reads about 16 degrees advanced at idle. Directions say to disconnect the electronic timing thingy when setting the timing, so with it disconnected, the timing dropped to about 4 degrees retarded. It says to set timing to 0 degrees advanced with the the timing thingy disconnected, so I did... by rotating the distributor a little. I then hooked the electronic timing thingy up and it reads quite a bit more advance now... do you think that will help lower the HCs??

Bills,
How can I get the water temp up higher without fear of damaging something?? Anyone know what the correct temp thermostat is for that year? It's a 350 motor that had AC and has an auto tranny.

Thanks again,
Bill C.

Hi Bill
More advance equals more H.C.
If you just missed the test by a dab retard the timing to 8º and it will be good to go.

Jim

JIm,
That's what I kinda thought, but wasn't sure, so thanks for pointing me in the right direction. I think I'll retard it a it more and what to you guys think about maybe blocking off the radiator air flow a bit to try and get it hotter? I never thought I could have a motor run too cool!!

Thanks,
Bill C.

if your not to far out..... first thing is do you have a clean air filter ?? is oil changed ?? are you running the LOWEST octane in the car ?? burns faster LESS HC .. you can also put in a higher flow pcv valve or create a small air leak to lean out mixture ... can't got to far as it will drive up NOX .. but like I said if your not to far out :D

The correct thermostat temp for your Sub is a 195 degree stat.

HC is raw unburned fuel. When's the last time you did a good tuneup? High HC is death to your new converter.

Well, I'm going to try again tomorrow, so wish me luck! Here's the latest setup for the re-test: backed off the timing to about 8 degrees retarded with the electronic timing thing disconnected which gives about 12 degrees advanced with it hooked up. The truck has a new air cleaner on it, albeit the paper type. Don't know about the tune-up or oil change, I just bought the truck several weeks ago! The fuel is low, so I'll put in some low-octane stuff before I go for the test. I usually use the mid-grade stuff. I've also blocked off over half of the radiator with a piece of cardboard to try and get the engine temps up. Hopefully that will get me by so I can at least get this beast registered! Then I'll work on the rest of the tuneup.

Is there any quick home method of checking for HC after I get this thing past the emissions police?? I'd like to get it tuned up and running as best I can, but don't want to hurt the new convertor!

Thanks again,
Bill C.

Whoo Hoooo!!

I passed with flying colors! Thanks for the help guys!!

Bill C.

B.C. very good graemlins/beers.gif
Now get the timing back up to 18º and have some fun graemlins/thumbsup.gif

Jim

It's already back up Jim... thanks for the reminder! :D

I am still going to look at the thermostat and get the correct 195 degree one in there if not already.

Thanks again guys,
Bill C.