help with my carb
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CF Beginner
Joined: May 2009
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From: colorado
help with my carb
I have a 1984 chevy g-20 with a 350, my question is how do i adjust the choke plate on the carb to be open. the problem im having is if the van sits for awhile the plate closes and then when i go to start it up it runs rough and blows black smoke due to not enough air.after a few minutes it clears up and runs fine except for a little hesitation.i would like to avoid this every morning and after work every day, so if anyone can help me with this i would really appreciate it.
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Joined: Apr 2008
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From: Pasadena,C.A.
that plate is supposed to close , its the choke on the carb, if it doesn't close your gonna have alot harder time starting the van.
the black smoke is extra / to much fule in the system, do you pump the pedal more than one befor you start the car ? it sounds like your flooding your engine .
you have an manual or electric choke ?
the black smoke is extra / to much fule in the system, do you pump the pedal more than one befor you start the car ? it sounds like your flooding your engine .
you have an manual or electric choke ?
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Joined: May 2008
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Most automatic chokes have a thermostatic spring coil(bi-metal) much like a honeywell house thermostat.
If memory serves, adjustment is simple. With the engine cold,merely loosen and turn the black round casing on the side of the carb(looks almost like a black jar lid) CW no more than 1/2 to 3/4 turn-{may be CCW depending on where it is on the carb}until you can see the choke at the top of the venturi barely close. Then when the engine heats up, it should adjust open automatically.
If memory serves, adjustment is simple. With the engine cold,merely loosen and turn the black round casing on the side of the carb(looks almost like a black jar lid) CW no more than 1/2 to 3/4 turn-{may be CCW depending on where it is on the carb}until you can see the choke at the top of the venturi barely close. Then when the engine heats up, it should adjust open automatically.
Last edited by therewolf; Jun 10, 2009 at 10:51 AM.
CF Veteran
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From: Albuquerque, NM
That new is probably electric actuated and not heat tube type. That old (25 years)is probably that its shot or getting tired by now. My moneys on the electric heater not opening it fast enough after he starts it. Butterfly has to work smoothly too.
Just got to thinkin' (and yes it was almost painful), could the bi-metal spring be broken and allowed the butterfly to hang loose and open?
Just got to thinkin' (and yes it was almost painful), could the bi-metal spring be broken and allowed the butterfly to hang loose and open?
Last edited by Gwampa; Jun 13, 2009 at 10:44 PM. Reason: additional idea
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I am assuming you have a Rodchester 4 bbl carb, if so the problem is probibly the choke pull off valve, located on the side of the carb.It is a round plastic vacuum operated valve.It opens the choke a little so it can get air, but not too much then the choke opens as the engine warma up.
To check it out apply vacuum to the port on the valve and see if it opens about 25% if not replace it.
To check it out apply vacuum to the port on the valve and see if it opens about 25% if not replace it.
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