what kind of choke does my 75 chevy c20 have ?

my truck starts runs rich wants to die idles low, tried to adjust the idle nothing happens.

i took of the air filter and opened the first flap and it idled alot better why is that ?

i know a little about engines but not too much about carbs.

please help

 

the flap you opened is the choke valve. when the engine is started, the choke is all the way closed but then is pulled open by a vacuum break. beyond this, it depends on what model carb it has as to specifics on choke and vacuum break settings and how it is heated. more research...more info

 

Pull your air cleaner off, and look at the side of the carburetor, do you see a shiny black cover about 2" round often on passenger side. Should have 3 rivets or screws holding it on to the side of your choke housing, if that's the style choke you have. If so, that is a thermostatic coil in there, that aids in pulling the choke off as engine warms. Get back to us, & if that's the case, we'll help you adjust that choke.

 

Sometimes one of the heater hoses is routed alongside it in a bracket to provide temperature sensing for the warm-up.

 

if it is a v-8 then i'm guessing a q-jet carb. at any rate, as stated, probably a round black thing on the pass. side with two wires. one black(ground) and one red(12 volt). cold, the choke plate(the one you saw under the breather) should be closed to about 1/16 inch.(as carguy stated they vary with models but this will get you close). after it warms up to operating temp., it should be fully open(straight up and down). if this isn't happening, the choke heater could be defective(choke is about 30 bucks). be sure to check the ground wire to see IF it is grounded and the pos. wire for voltage(with switch on). if it is the orig. air cleaner, there are vacuum hoses attached that go to a cold start device/flapper. you NEED a HAYNES manual!! Good luck.