Car will not accelerate under load, sometimes backfires

[kirkp]

Car is a 83 Hurst Olds stock 307.  Bought the car and it ran fine when I bought it other than it wouldn't idle very well.  It sat in my garage for a few months before I had time to mess with it.  I tried to turn the idle screw up a little and took the car for a ride and then it wouldn't accelerate.  About 2000 rpm it would fall on its face no matter how hard or easy I pressed the gas.  If I stayed in the pedal it would sometimes backfire.  Seemed to me like it was running out of fuel.  Thought I would start with some easy things and went with plugs, wires, distributor cap and rotor, plus changed out all the vacuum lines.  Still exactly the same.  Ordered a carb kit from Cliff and went through the carb.  I have rebuilt other quadrajets but never a CCC.  The idle mixture screws were way off of the starting point of 4.5 turns out.  The right side was 2.5 turns out and the left side was 1/4 turn out.  I reset those to the 4.5 turns out and the idle is nice now.  The acceleration problem is still the same.  Does anyone have some suggestions?  I don't know where to go next.

[77cruiser]

If the mechanical advance is rusted & sticking it might be the cause. Did you pull the cap & rotor to check it?

[Cliff Ruggles]

Disconnect the plug to the M/C solenoid and see if things improve.  If so the solenoid isn't functioning properly and causing lean condition......Cliff

[kirkp]

Cliff, I will try that. One thing I noticed while rebuilding the carb is the stop on the air horn for that M/C solenoid was threaded out quite a way.  I looked at some videos of other people tearing down these carbs and theirs did not look that far out. I didn't move it because I didn't know what a starting point setting was for it. I moved it a little one way and then back and it turned really easy.  I'm not sure if this could have moved when trailering the car home.

[kirkp]

Here is a picture of the stop. 

[kirkp]

Ok, that's what the problem was.  The rich stop was all the way down against the solenoid plunger. I made a tool out of a piece of 3/16" brake line to turn the screw out until it seated.  Then I set it to 4/32" of travel.  The tool I made by cutting a piece of 3/16" brake line with a tubing cutter then tapping the cut end gently over the screw.  I made a short piece the same way to hold the screw in place.  Only thing additional I did with the short piece was squeeze the upper part of the line with vice grips to flatten it just enough to fit tight in the hole.  Then I gently tapped it in until it seated.  Hopefully that will hold the screw from moving.  My only question now is the lean stop.  I have the travel set, but am I setting that off of a good lean stop setting.  I set the lean stop setting to what it was when I took the carb apart.  Obviously someone has been tinkering with this carb and I do not know if the lean stop is set correctly

[Cliff Ruggles]

For sure that rich stop is WAY too low.

I usually set them at the max-rich position for initial testing.  Seldom do you have to bring them down very far for the best final adjustment.......Cliff