[murrsue]

My project vehicle has a 350 out of a 79 Chev 4x4. It's bone stock with the original quadrajet 4 barrell. (17058213, 0738 BJB are the #'s on the carb)
Last week I got the project to the point that I could start the thing up. It hadn't run in 3 yrs. Using a gas jug for a gas tank, and after a few squirts in the carb it fired right up great. I've had it running several times to get it up to running temp and check it over for leaks and can't drive it yet except to move it in and out of the shop.
Anyways it's starting and running great but I think it's too rich. My shop and my clothes have that rich exhaust stink and the new exhaust has black build up at the tailpipes. I checked the two air/fuel mixture screws, one side is out 4 and the other is out 2 1/2. I've read here before that they should be the same on both sides and about 2 to 2 1/2 turns out. Just wondering what I should try and how do I adjust it properly? Is leaner in or out on the screw?

[curtis73]

If it was running correctly when you parked it, the screws didn't magically change. They might not be right, but always look to soft parts on a carb, not hard parts. The jets and rods didn't change, nor did the idle mixture. What did probably happen is that the gaskets are cracked, the float might be sunk, the needle and seat probably gummed up and are sticking either preventing it from opening or closing... or both.

Take it off, clean it, buy a $15 rebuild kit and put it back together.

its also possible that your ignition system isn't up to snuff and its not properly igniting the fuel, or igniting it late making a lot of unburned fuel come out the pipes.

[murrsue]

I never witnessed the motor running before now. I bought a wrecked low mileage truck on tip from the former owner that it was a good motor. I pulled it, cleaned it up, replaced gaskets, wires plugs, cap, etc., and painted it. A carb rebuild might be in order though but I think I'll play with it a bit. I'm wondering if that screw turned out too far would make it too rich?

[McLeay F1]

you have a vacuum gage? hook it up to a port on the carb or intake with the most vacuum turn those screws in and out (don't bottom out the screws) till the vacuum reaches its maximum point about 10 to 15 inches if its stock. set idle to taste if its still to rich it needs a rebuild and I don't remember a carb kit being 15 bucks in Canada more like a $100.0 for a good one. if you don't have a vacuum gage heres the bushman's way. set idle to about 600 to 800 rpm turn the first screw all the way in till it just about wants to stall then back it out till it runs its fastest repeat on other screw that should keep you busy.

[curtis73]

Originally Posted by murrsue

I never witnessed the motor running before now. I bought a wrecked low mileage truck on tip from the former owner that it was a good motor. I pulled it, cleaned it up, replaced gaskets, wires plugs, cap, etc., and painted it. A carb rebuild might be in order though but I think I'll play with it a bit. I'm wondering if that screw turned out too far would make it too rich?

Ah, I gotcha. Yes, that adjustment could cause a rich idle, but not really anywhere else. Once you barely crack the throttle the contribution made by the idle adjustment is so small it wouldn't be noticeable.

I would give it a few good whacks with a screwdriver handle to try and dislodge the float if its stuck.

I understand that Canadian parts are more expensive than the exchange rate suggests, but down here, even the good Walker brand ones that come with new floats are $25. Shop around and you might get lucky and find one for under $100. Heck, down here we can buy a rebuilt carb for $50 Not to rub it in or anything

[McLeay F1]

the whacking with screw driver works some times. my old trick was to spray carb cleaner down into the vent tube and rev the crap out of it

it must be nice to live down there in LA rebuilt carbs for fifty bucks and so many other things for cheap rebuilt carb from popular parts store $324.77
$80 core charge plus are great tax tax for a grand total of 370.23 plus 10 bucks in the tank to go get the carb and its just a stock rebuilt quadrabog

[curtis73]

Oh well. I'm gonna be a canuck someday soon. I'm spending more time up there than I am in the US, and I like you guys better

Got a house for sale per chance?

[McLeay F1]

make sure you bring lots of speed parts with ya we will want to do some trading

[murrsue]

www.carburetor.ca is the Carburetor Doctor out of Alberta Canada. The site has great info on identifying carbs,etc. and prices look reasonable. $27.08cdn. for a carb kit for my Q-jet although that doesn't include the float or choke pulls.
Which brings me to my next query. How hard is it to rebuild a carb? Is this something I want to tackle on my own?

[McLeay F1]

take apart, clean, add new parts reassemble according to instructions from kit. I guess if your driving this car day to day and depend on it. get a new carb your done and trouble free in about 20 minutes. if this is the first carb you have rebuilt in your life and you have no one for guidance. its a wee bit of a learning curve like anything. you installed the motor you should be able to rebuild a carb. your certainly not going to break it. ma by start your eye brows on fire. just kidding

[poncho62]

I would judge if its too rich, until you start driving it.....Just putting it around the yard is going to load it up anyways....give it a decent run and then see if its still rich.