1969 K10 / Quadrajet Question / Missing Screw Identification
 

I have a 1969 K10 with 350 V8, 4 speed, PS and PB. The engine has an original looking Quadrajet carburetor on it. The stampings on the carburetor body are: 7045583 YZ 1276

On the front of the carburetor is a threaded hole. I need help determining what it is for and should it have a screw in it or be plugged. I’ve attached two photographs for reference. The screw hole is located on the right hand side right above a rubber port plug.

Any information would be appreciated.

Side Note: Engine starts and runs OK. It however is idling fast at both cold and hot engine temperature.

Thanks.

Re: 1969 K10 / Quadrajet Question / Missing Screw Identification
 

This is what I see looking at your picture: I don't know what the screw hole is for. It seems like I have seen those before.

Is that an oil leak or fuel leak on the right side below the carburetor? IT could be leaking from the throttle shaft or could be leaking vacuum from your carb base gasket. Also, are the plugged vacuum lines really plugged? One of those should go to the distributor I am thinking. also maybe you are running too lean or the idle screw is not set properly, hence the running high

Re: 1969 K10 / Quadrajet Question / Missing Screw Identification
 

Fast idle usually indicates a vacuum leak

Re: 1969 K10 / Quadrajet Question / Missing Screw Identification
 

The screw hole is for the anti diesel solenoid bracket.
High idle hot and cold can be caused by vac leak, too rich choke setting, or high idle screw.

Re: 1969 K10 / Quadrajet Question / Missing Screw Identification
 

Yes - there is oil that has leaked on the top of the intake manifold. Figuring out what was causing that was next on my list - so thank you for your comments. I’ll also check the vacuum lines and plugs.

Re: 1969 K10 / Quadrajet Question / Missing Screw Identification
 

Dieseling has also been a problem. It doesn’t do it when the engine is cold - but it does it when it’s hot. Should there be an anti diesel solenoid and bracket?

Re: 1969 K10 / Quadrajet Question / Missing Screw Identification
 

Find and fix your high idle and you won’t need a solenoid.
Remove the two bolts on the intake and put sealer on them to cure the oil leak.

Re: 1969 K10 / Quadrajet Question / Missing Screw Identification
 

OK - thank you.

Specifically - which two intake bolts are you referring to?

Re: 1969 K10 / Quadrajet Question / Missing Screw Identification
 

The 2 right beside the carb.

Re: 1969 K10 / Quadrajet Question / Missing Screw Identification
 

The anti-dieseling solenoid was usually included on AC equipped trucks. It would bump up the idle speed when the AC comp kicked in. Some later emission motors had them because the idle timing was so low that the idle screw had to be screwed in so much the throttle plates were too open. When the power was off, the solenoid relaxed and let the throttle close.

The line from the carb front to the dizzy is normally the size of the one off the front top with the screw in it and is normally just a press on fit.

Might be a good idea to replace both the intake and valve cover gaskets. The PB booster can be a source of vacuum leak.

Check your idle timing as well.

Re: 1969 K10 / Quadrajet Question / Missing Screw Identification
 

It's mounted like this:

Re: 1969 K10 / Quadrajet Question / Missing Screw Identification
 

Ok, your carb is not original...it is from a 1975 truck, which is not necessarily a problem.
As already mentioned the screw hole is for the anti-dieseling solenoid...solved, no problem.
As for the fast idling...before you adjust the carb you need to get a timing light and correctly check and set the timing on your engine....always before you adjust the carb. always.

Then, start by checking the idle screw on the drivers side of the carb to make sure it is not dialed in too far....is it touching always? check.
Then, if not touching you will need to check the fast (choke) idle screw on the passenger side of the carb...partially hidden way down low...is it all the way in or where is it at?

Also, I'm wondering what port on the carb your vacuum advance to the distributor is tied into ? ....hopefully you don't have it connected to full vacuum.
Usually the vacuum advance is connected to that plugged port right near the anti-dieselling solenoid tap that you have identified.
Check this out and let us know what port your vacuum advance is tied to...because if it is always advanced it will increase your idle speed.

...ok, lets start there.

All good
Coley:chevy:

Re: 1969 K10 / Quadrajet Question / Missing Screw Identification
 

Coley, Thank you for your comments. I’ll run thru your list and post what I find. I also started a separate post asking about all of the vacuum lines and ports. Thanks again.