Help with carb

[Chisholmcody]

Hello my name is Cody and I have been working on my 1978 chevy cheyenne pick up with the l6 250 in it. We have just had the carb rebuilt and they left the idle stop solenoid unplugged. Every time I plug it in it idles very high. Higher than the fast idle when the choke is on. Also the truck loves to stutter when I push the on the gas after a dead stop (with out solenoid plugged in). Another issue I have been having is after a long drive the truck idles super rough and wants to die at stop lights and I'm always having to re adjust the idle to around 750. It also runs rough for a good 3secs after turned off. And I am also wondering if this has to do with the slolenoid being unplugged.

Any help and or answers will be greatly appreciated.


Also carb is rochester 1bbl monojet

[bd]

Hello Cody.  Welcome to the site!

How did it run before you had the carb rebuilt?  You need to check for vacuum leaks - excessive air is entering the intake manifold. 

[Chisholmcody]

I had it rebuilt in April and we have looked for vacuume leaks and every thing checked out

[bd]

Nonetheless, all of the symptoms point to too much air. 

Why did you have the carb rebuilt?

[Chisholmcody]

The truck sat in my grandmas garage for 20 some odd years and was only ran around Christmas time to get a tree and it ran very rough and died at every stop sign or light..

What about the idle stop solenoid? Is it required

[bd]

The idle stop solenoid, when properly set, controls normal "curb" idle speed.  When ignition is switched off, the solenoid deenergizes allowing the throttle plates to close almost completely, so the engine doesn't diesel.  From memory, "base" idle speed with the solenoid unplugged should be ~400 RPM.

[Chisholmcody]

Is the base idle speed controlled by the hex screw or the nut on the solenoid

[bd]

LOL - you are really testing my memory!  From recollection... with the solenoid energized, turning the body of the solenoid adjusts 'curb' idle and is the primary adjustment - with the solenoid deenergized, turning the screw adjusts 'base' idle and is the secondary adjustment.  Details on the carburetor and adjustments are available in Section 6C of the 1978 Service Manual.

[Chisholmcody]

Is the "low" idle the in gear idle and then the curb is the out of gear ?

[bd]

Automatic transmission:  both adjustments are made with park brake firmly set - transmission in Drive.

Standard transmission:  both adjustments are made with park brake firmly set - transmission in Neutral.

[thefarmboy21]

Turn the solenoid out. BUT I just rebuilt my monojet on my 292 and it was junk after I tore it apart. The carb body was starting to deteriorate, the jet was trash and it pours fuel out the accelerator pump linkage. It was being held together by the tar like substance pretty much. It had no power afterwards and the jets/metering rods available aren't big enough for the 292. But it was only going to hold me over til spring anyway....so plans moved up a few months lol.

I pulled the whole motor yesterday and will be droppin In a 350.

I'd look into a street rod version of a 1bbl or into an OFFY, edelbrock intake for larger carb.

[Chisholmcody]

Thanks bd for the help gunna look at it tomorrow and farm boy if I can't get it to work maybe I'll bite the bullet and get the 350

[Chisholmcody]

Just got finished. Got the truck to idle around 850 out of gear and 600 ish in gear
Thanks for all the help

[bd]

You're welcome!  Does it shut down w/o dieseling, now?

[Chisholmcody]

Yes it stopped desileing and is working very well