Carb issue?

[KCGarage]

Hey guys just rebuilt the motor after losing a rod bearing. After assembly and start up it feels like she's gutless and sluggish. Upon looking around it seems only one butterfly on the carb is opening with the throttle linkage, the one closest to the head isn't opening. I tried opening it with my finger thinking the shaft was broken but not the case. Got it to open and it snaps back shut with plenty of tension. Just wondering if this is normal or if I have an issue. Any help will be appreciated. She is an all original 80 D50 G52B motor.

[geezer101]

This is an easy problem to diagnose and fix (and common). Take the small vacuum elbow hose going from the back of the carb to the vacuum actuator that controls the secondary butterfly shaft, attach a longer hose to that vac actuator, open the throttle by hand and apply suction with your mouth. If the secondary pulls open but won't hold vacuum - the diaphragm has split. Undo the retaining nut that hold the secondary vacuum actuator in place, remove the 'c' clip that holds the actuator rod on the linkage and you should be able to gently pry it out and replace it without removing the whole carb from the manifold. Easy fix

[KCGarage]

That is what I'm talking about. Thanks geezer. I'll give that a try next.

[KCGarage]

IMG_4675.jpg
Shes coming along nicely

[geezer101]

Seems to be the time of year where stuff happens in a mostly productive way. Looks tidy KC!

[pennyman1]

I see you resolved the manifold issue for the air pipe - what did you use?

[KCGarage]

IMG_0300.jpgGot a stainless plug from fastenal and put high heat RTV on the threads and locked her in there.

[KCGarage]

Geezer, when I open the throttle and apply vacuum via my mouth, the butterfly opens slowly and it only opens about 45° not the full 90° like the main butterfly

[geezer101]

Yep it's toast. Replace it and you should have full throttle again. And a friend has just informed me of a 'better' fix for a failed exhaust gas recirculation pipe. Re-use the threaded bung that holds the pipe in place and install an O2 sensor in there. Add an O2 monitor and now you can keep an eye on your air/fuel mixture!

[KCGarage]

So the real question is where can I get another actuator? anybody have a part number? I hope I don't have to hit the pick n pull to try and find one or drop an entire paycheck for one.

[KCGarage]

I found a couple on eBay brand new for $110 and referbed for $65. I can't believe that little booger is so hard to find and spendy

[KCGarage]

So now that the secondary vacuum is fixed, she's little hard to start, but when I get it up to temp the choke stays closed. I let it idle for 20 minutes and the choke is still closed. So I propped it open at temp and gave it some throttle and it just fell on its face and stalled. The MAS was out 5 turns from completely closed when I started this "diagnosis". The questions are: 1) it appears there is linkage for the choke to hook up to but mine isn't. Anyone have a picture of one hooked up? 2) what is the settings for the MAS? I'm at sea level if that helps. I'm guessing the previous owner was trying to comprimise the mixture for the secondary diaphragm not operating and the choke staying closed. Any guidance that you guys can decipher out of my ramblings will be greatly appreciated.