Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem
Edel 1901, AMS out, Still Lean at Idle
blazer74:
Standard set will not reach the restriction for the idle tube. You will need to remove the idle tubes to use those drill bits.
Cliff can supply new tubes also.
You can go to amazon and do a search for taper length drill bit # 65 for example and buy them individualy, they don't always have all the sizes tho.
Cliff Ruggles:
Main jets and metering rods are not part of the idle system. Idle tubes, DCR's, and idle airbleeds are the main players.
Having no control over idle speed indicates a vacuum leak someplace, provided the throttle plates are all completely closed.
I'd remove the baseplate and verify fully seated throttle plates, and if you still don't have idle speed control you've got a vacuum leak someplace.
The 1901 doesn't have a generous idle fuel set-up, and if you don't have full control with the mixture screws after making sure everything is in good working order, then you'll have to go in and modify the idle system accordingly.
I'd also set the float at 1/4" and forget about it. Float settings effect fuel delivery, too high or too low can have an impact on tuning......Cliff
bry593:
Not many vacuum taps on this 1970 Chevy Coupe. I'll cap the PCV and advance port, and also the booster and TH400 modulator on the manifold and try again. If no change, then will remove unit for closer inspection.
Pulling the throttle body is probably a good idea since it will allow me to check the gasket hole pattern as well as torque on the screws. I assume the gasket is probably correct since both mixture screws function.
That is not good news about my drill bit index. Would a "jobber" set be long enough?
bry593:
Off topic: I was little surprised to see a '75 Forumula on Cliff's home page. Very, very few of these cars around. I have one and have owned it since 1987.
Cliff Ruggles:
No need to cap off the PCV, just remove the valve and put your finger over the end of it. It adds a very small amount of air at idle when working correctly......Cliff
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