Failed emission, c02 at idle 25% to high

[Rolled]

I need some suggestions on where to start to fix this.

1982 K20
350
465
m code heavy emissions
no cat, egr, or canistor from factory

Here are the results of the test -

------------HC ppm--------------C02%
------------Limit-----Reading-----Limit-----Reading
1000 rpm---1000-----141---------2.00-----2.48<----Fail
2500 rpm---1000-----63----------2.00-----1.58


Where would you start to fix this? My guess is to rebuild the carb and adjust it as good as I can.

The motor runs very well and appears to be good enough to pass. It was a mess when I bought it but I got it running very well and I am pretty sure the internals are *good enough*

I just need this to pass before I put a emission illegal motor in


Anyways, any advice before I start throwing money at it?

 

[fatbob]

I just went through the same thing. Put some acetone [see actone thread] in the tank, 2.5OZ per 10gal. Adjust carb with vacuum gauge for highest vacuum, put in new air filter and I passed.
But here is a good diagnostic page.

http://www.recarbco.com/technical/smog/smoginfo.html

PS. I still have those transmission parts for you. Did you ever do anything with that 305? Email me and I'll get 'em to ya.

 

[gmtech954]

you could also put 2 bottles of rubbing alcohol in at 1/8 tank itll pass with flying colors without a 5 gas analyzer its hard to tune perfectly for emmisions

 

[tRustyK5]

Turn the idle speed up to 800 or so and try again. That will clean up your idle numbers...

Rene