75 Eldorodo Rough Idle

[stowe75]

I recently rebuilt my carb ..took it apart last night and cleaned again just to double check. replaced on the Eldo , now car runs beautiful at perfect choke as choke opens it idles rough and will die. I did not touch the idle speed screw. What is a good starting point for the idle mixture screws.  On a side note it does not idle great  at full choke either Thanks

[35-709]

The 1973 shop manual says 6 turns out initially for the mixture screws, your 1975 manual may say something different since your Q-Jet is a one year only piece.  Idling smoother while the choke is on suggests a too lean mixture because of the mixture screws being screwed in too far or a vacuum leak somewhere. 

[stowe75]

I got it figured out. There was a vacuum leak at base cleaned and replaced gasket. Running pretty good. Now another question Is there a starting point for the choke to be in on cold start. I believe it is fully open until tap on the accelerator Once closed is it suppose to be completely closed or a small amount open .Is there a procedure for setting the electric choke? Also any pictures or diagrams of the choke linkages  would be so helpful.  Thanks

[Julien Abrahams]

For my '67 vmn quadrajet the choke valve is fully open when the engine is cold. Mine has the "choke stove" on top of the intake manifold. Before starting, you need to c!ose the choke by stepping on the accelrator once. The bimetal spring in the choke stove will make the choke valve close completely (via the choke rod).After the engine starts, manifold vacuum will open the chokevalve slightly. As the enige warms up, it heats the choke stove eventually pushing the choke valve completely open afterwhich one tap of the accelrator will kick it to base idle. The last is only necessary when you have oushed the gas down far enough yet (for example during driving).

["Cadillac Kid" Greg Surfas 15364]

With the 3 screws holding the choke coil cover loosened enough to move it and the engine cold what I typically do is (with the throttle slightly cracked ((engine off of course)), I turn the cover clockwise until the choke is fully opened and then slowly turn it counter clockwise (to the left) until the choke is fully closed. I then turn the cover another 1/8 inch as determined by the alignment marks on the cover and the choke body.
With the choke set on startup the high speed idle screw (hidden below the choke on the passenger side of the carb) should be adjusted to (I use) 1800 RPM. 
When the choke is fully opened, the high speed idle mechanism will be out of play and the "speed" adjustment is on the driver side carb linkage. 
IF the car starts cold and runs well but stalls due to low idle speed soon after go back to the choke adjustment and turn it one notch further counter clockwise and see how that works out.  Very small adjustments in the choke coil make a big difference.
Greg Surfas

[stowe75]

I noticed a vacuum line fitting on the base of the choke housing attached to the side of the car. The choke is electric. What does this port attach to also is it needed?  Car runs nice now but has about 5 seconds of run on after the ignition is turned off.

[The Tassie Devil(le)]

That length of run-on after shut-down is of concern.

Sounds like the Throttle Solenoid is disconnected, or set too high, or is being used as a throttle stop, instead of being used as was intended, that being a throttle shut-off when the ignition is turned off.

The way it works is that with no power on, the throttle is completely closed, and as soon as power is applied, as in Ignition 12 Volts, the electro-magnet within the unit, opens the throttle linkage to idle speed.

Bruce.  

["Cadillac Kid" Greg Surfas 15364]

75 does not have an idle stop solenoid.  There is no vacuum fitting on the choke housing for 1975.  If you see something that looks like a vacuum fitting ON THE CHOKE ITSELF, you either have incorrect parts or something is installed incorrectly.
Greg Surfas

[The Tassie Devil(le)]

Thanks for the information Greg.

Bruce.

[stowe75]

Here is a picture of the electronic choke with the vacuum nipple .

["Cadillac Kid" Greg Surfas 15364]

Can't see from the picture that that nipple is actually a part of the choke rather than the carb base.  Regardless, cap the nipple and see what that does to your idle.
Greg Surfas

[stowe75]

Thanks ,
   I just looked again on choke not carb base. The Idle is fine now  just have the run on when shutting off.