Quadrajet Help?!

[72 Blaze]

Hey Guys! Ok, I sold the Blazer! sad sad day! But, I picked up a 1979 K1500 for half the money. I have already posted a couple of pics. Here comes the kicker! I drove it home and I was amazed at how well the truck rode and drove. I am the 3rd owner. The original owner that bought it new has passed and the guys next door neighbor bought it from him... Anyway long story short the truck sat in both guys basements most all its life. It's got 57K miles. The air works and the truck is tight. I found the original tag bolds "still in the paper wrapper" in the glove box along with all the original paper work. I have been driving the truck for a couple of weeks now. It's started to smoke a little and that worried and bothered me. I carried it to have the Valve Seals replaced! Luck me they were brand new. I guess the old dude pulled one over on me. But, its not his fault its mine for not driving it longer on my first test drive. Anyway, now when I crank it up cold "fresh start of the day" it seems the choke is not right.. Smokes really bad and then clears up and runs pretty good. I dont even know why he would have messed with the carb, but it was not doing that before I took it to the shop. Any ideas? I have no clue when it comes to the Quadrajet. All I know is that it didnt do this before I had it worked on. By the way, He told me to run some restore in it... I cant afford to replce the rings right now! I have a babby on the way!

 

[76zimmer]

what color is the smoke?

Black, rich carb
Blue, oil from ring blowby or valve seals/guides...possibly intake manifold crack.

 

[72 Blaze]

Well the first smoke that I thought was the Valve seals was blue.. Now I think it's a ring after having the seals looked at. Problem is now its a black carb smoke running really rich when it's first started in the am. It clears up and runs fine, but the first start up is rough! Something in the choke I'm guessing, but it was not doing that until I had the Valve seals checked. Im just trying to figure out what could have caused the carb problem from having the valve seals checked!

 

[76zimmer]

With the engine cold, check the choke plate...with ONE pump of the acc. linkage it should close, but only with enough spring pressure (the spring is in the round housing on the pass side of the carb) to just close it. Pump the acc. one more time (check for fuel when you pump it by sticking your finger in the choke plate to open it and verify the acc pump squirter is working) let the choke plate close and try to start the truck. Does it try to start, but not stay running? Does it start but runs very rough and tries to stall? Let us know as detailed as you can what exactly it is or isn't doing when trying to start it.

 

[72 Blaze]

Ok I had some time today to look at the carb. I did exactly what you said. One pump the choke closed as it should. Another pump and it opened a little. I started the truck, first time today. And it starter right up and filled the shop with black greyish smoke. I didn't touch the pedal and the truck ran for about 20-30 sec and then choked its self out. I got it to crank back giving it gas and it clean it's self out.... After a min, I didn't drive it anywhere. It's just crazy becouse it just started doing this?

 

[76zimmer]

Check for a vacuum line being off on a small vacuum canister about 1.5" diameter on the side of the carb...that is a choke pulloff....when the engine starts it creates vacuum, and the little canister w/ plunger pulls the choke plate open slightly to allow more air into the carb so it won't be so rich. If that is hooked up, check the linkage going to the choke plate, to make sure it isn't binding. post up with what you find.
You can also manually open the choke plate with a screwdriver (make it a big one that won't fall into the carb opening) Start the truck as before then have a helper or yourself if your quick open the choke plate about so there is about 1/4" opening on the plate from the carb body. If the engine sounds good and isn't puking black/grey smoke after doing that, then it is a choke issue to be worked out.

 

[6872xtc]

This isn't related to the carb problem, but if the blue smoke keeps up, check the vacuum modulator on the trans. This is of course assuming the it has an automatic.

 

[72 Blaze]

I just checked the modulator. It's good! I'm guessing it just needs to be rebuild or buy a new carb. This critter gets worse gas mileage than my old blazer with 4:10 gears and 35's! Something has got to be wrong some where. It's crazy. I have not had a lot of time to put in it, so I'm thinking just drive it until it dies. It's not my primary driver. But I wanted to spend money on other stuff.... Not unexpected motor stuff!

 

[wazzabie]

Check your oil level.

 

[72 Blaze]

Will having to much oil cause the carb, choke to act this way?

 

[wazzabie]

I had too much oil and I had the carb setup wrong at first so it was running at a high rpm. So much smoke was coming out of it.