Quadrajet too rich!

[DemarioM]

Good evening. I have an 85 c10 with a 305 in it. It's my dream since I was a child. The carburetor I've got is I quadrajet 17085226. I'm inquiring because I'm having a hard time passing emissions due to it's running too rich and, I don't know what else I can do to correct it. I'm pretty sure at this point I just need to change the jets due to the altitude. I live in Aurora Colorado and the altitude is 5,403 ft. I need help purchasing the correct jets. I'd really like be able to drive my dream truck legit but I can't get a registration until I pass emissions.
PLEASE HELP!

 

[C10MixMaster]

Good evening. I have an 85 c10 with a 305 in it. It's my dream since I was a child. The carburetor I've got is I quadrajet 17085226. I'm inquiring because I'm having a hard time passing emissions due to it's running too rich and, I don't know what else I can do to correct it. I'm pretty sure at this point I just need to change the jets due to the altitude. I live in Aurora Colorado and the altitude is 5,403 ft. I need help purchasing the correct jets. I'd really like be able to drive my dream truck legit but I can't get a registration until I pass emissions.
PLEASE HELP!

to rich at idle cruise or acceleration? do you have a copy of your emissions test it would help

 

[DemarioM]

I have about 7 copies, the best I've done so far is..
HC 4.7O
LIMIT : 4.5
CO 90.03
LIMIT : 45.00

 

[C10MixMaster]

I have about 7 copies, the best I've done so far is..
HC 4.7O
LIMIT : 4.5
CO 90.03
LIMIT : 45.00

are these idle readings or do they do a dyno run and take reading?

 

[DemarioM]

These are on a dyno

 

[C10MixMaster]

These are on a dyno

OK things that's can cause hi CO and HC under load

problems with the ignition system causing a miss under load. plugs use only stock type plugs nothing fancy, no platinum's , no iridium's , no multi tipped plugs they are just going to cause you problems. check you plug wires , I like to use a spray bottle and mist the plug wire if there is a bad spot in the wire you will get an audible tick and drop a cylinder. Also make sure your mechanical advance is working.

If your ignition system is good and it is a carb problem . things to look at are float level to high will go rich, primary rods bent, power piston stuck, mains jets too big. If it is a carb issue I would build it by the book first before changing jets or any think else.

the books are here https://www.gmsquarebody.com/threads/1973-1991-service-manuals.14499/

 

[bob seifert]

Your carb 17085226 has a solinoid in it to cause a double pump in the idle circuit when cold. If its stuck open that maybe the problem.

 

[peats]

emissions on a 30 something year truck??? WTF?? move to a friendlier state.

 

[Ricko1966]

Couple of things come to mind, check for vacuum/ intake leaks. Make sure all your vacuum hoses are routed correctly that truck should have like 0 advance at idle from an emissions stand point so a failed tvs, improperly routed vacuum line etc. can cause you to fail.Pull some timing out and fill up with 10 percent ethanol fuel just for the emissions test.

 

[SirRobyn0]

OK things that's can cause hi CO and HC under load

problems with the ignition system causing a miss under load. plugs use only stock type plugs nothing fancy, no platinum's , no iridium's , no multi tipped plugs they are just going to cause you problems. check you plug wires , I like to use a spray bottle and mist the plug wire if there is a bad spot in the wire you will get an audible tick and drop a cylinder. Also make sure your mechanical advance is working.

If your ignition system is good and it is a carb problem . things to look at are float level to high will go rich, primary rods bent, power piston stuck, mains jets too big. If it is a carb issue I would build it by the book first before changing jets or any think else.

the books are here https://www.gmsquarebody.com/threads/1973-1991-service-manuals.14499/

Your carb 17085226 has a solinoid in it to cause a double pump in the idle circuit when cold. If its stuck open that maybe the problem.

The above is great advice. Ricko, talks about timing, yes it would be a great idea to set it with a timing light, I'd only retard the timing for the purposes of getting it though emissions if everything else checks out first, but that is me.

 

[squarelyfe]

It's a 750 cfm carb on a 305... It's a little rich to begin with. Get yourself a Holley 600 cfm or Edelbrock if you can pass smog with one of those. Lean the af mixtures in and check timing.

 

[Blue Ox]

Check for leaking well plugs. Simple fix, but can lead to uncontrolled extra fuel in the system.

 

[Paladin]

Get a HOLLEY!!!!

 

[Matt69olds]

Get a HOLLEY!!!!

Right! Good luck getting that to pass an emissions inspection.

 

[Paladin]

Kool, it never fails, always someone out there that takes the bait!!!!LOL