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Q-jet electric choke

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Mastiff, Jul 23, 2003.

  1. Mastiff

    Mastiff 1/2 ton status Premium Member

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    Can anyone give me some advice on getting the electric choke set properly on my Q-jet? It's fairly warm out now, and the truck doesn't like to have any choke at all, or it won't start. Thing is, this has caused me to set the choke much more open than I think it should be. Do you expect the electric choke to be basically all the way open and 75-80 degrees? or should it be closed a little and then open with the electric heater?
     
  2. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    with a STONE cold engine first thing in the morning set the choke and adjust it till the top plate has about 1/8 inch gap from fully closed.
    At that setting the high idle cam should hold the regular idle stop about 3/32's off the stop. Should fire off and idle about 800RPM at that setting. then should climb to about 1,000 rpm in about 1 minute. After no more then 3 minutes in the summer the choke should be fully off.

    That's how I always adjust mine and never had a problem. I have more then once adjusted them like that on the bench after a rebuilt and never needed to touch it once I bolted it to the intake till season change.

    When your cold starting in warm weather try 1/4 throttle to set the choke before starting instead of full throttle. You might be flooding it. Then KEEP your foot off the gas and let it start on it's own.

    Also you may have a second problem that explains why your truck doesn't like choke at all when warm. Q-Jets are know for developing leaks in the casting plugs in the float bowl. The fuel runs down into the intake when this happens and basicly flood it. You might need to pull the carb apart and JB weld the casting plugs.
     
  3. Mastiff

    Mastiff 1/2 ton status Premium Member

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    Thanks for the reply. I swear I tried that, but I'll give it another shot tomorrow since I can't remember what the problem was.

    I just rebuilt the thing, and the manual mentioned the JB weld thing. I couldn't tell from the tiny grainy picture what I was supposed to do, so I just put it back together. I think the last guy who rebuilt it may have done it already. He already drilled out the choke rivets and all that, which made the rebuild pretty easy.
     
  4. Mastiff

    Mastiff 1/2 ton status Premium Member

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    Here's part of my problem. My rebuild kit came with a gasket to go between the plastic round cover for the choke coil and the body of the choke. I didn't have one before, but I installed the new one. It turns out that it was blocking the path to ground and preventing the coil heater from functioning.

    I don't understand it, maybe it's supposed to get ground from where the coil touches the linkage. It wasn't though for whatever reason.

    By the way, anyone know a source for a new electric choke coil with the plastic round part and connector? Mine works, but is old and crumbling apart. Wouldn't mind getting a replacement. The auto store I went to had no idea what I was talking about - made me look through the Holley catalog (which I did for a second to not be rude, even though I knew nothing would be in there...)
     
  5. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Yeah toss that out. Thats for if you had a hot air choke.

    On a hot air choke that bowl needs to be sealed because it pulls vacuum. On electric that port is blocked with a plastic plug (It's on the bottom front leg) if it has electric. You are right that the gasket is causing you a grounding issue. Pull it out.
     
  6. R72K5

    R72K5 Banned

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    if i would have seen thisd thread before grim got to it then id have said same things, electric choke is one of the best things around, i love them, that cover seal thing definitely is no good on electric models

    setting choke air valve to 1/8" gap when is cold in the AM one morning should be all needed to set it good /forums/images/graemlins/laugh.gif

    only other thing you may have to ever do then is run a good 14 guage wire directly from spade terminal labeled "IGN" on the fuse panel directly out to the choke /forums/images/graemlins/laugh.gif

    that will ensure that it always works with key on, never sit with key on and engine not running especially when engine is cold or youll have open choke in a matter of minutes with cold engine and if its cold out then well....
    you know.



    good luck!
     
  7. Mastiff

    Mastiff 1/2 ton status Premium Member

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    [ QUOTE ]
    only other thing you may have to ever do then is run a good 14 guage wire directly from spade terminal labeled "IGN" on the fuse panel directly out to the choke /forums/images/graemlins/laugh.gif

    that will ensure that it always works with key on, never sit with key on and engine not running especially when engine is cold or youll have open choke in a matter of minutes with cold engine and if its cold out then well....
    you know.


    [/ QUOTE ]

    Thanks for the help everyone. I think this grounding thing will solve my problem.

    On mine the choke power comes from a wire that goes through an oil pressure switch or something. It doesn't give 12V until the engine is actually running (I tested this). Prevents the problem you mention. Of course, it also makes stuff harder to debug since the engine always has to be running! /forums/images/graemlins/grin.gif
     
  8. Mastiff

    Mastiff 1/2 ton status Premium Member

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    Well, I think I got it pretty close now. It seems like it was actually better the way it was, for the summer anyway (it wouldn't start i nwinter, I'm sure). Until the choke opens all the way, the engine is not real happy. Do you guys mostly wait a few minutes before driving away? I normally don't go instantly from starter to drive, but I haven't been waiting 3-5 minutes, or whatever it takes for the choke to open up all the way.

    Maybe a summer setting and a winter setting is in order? Around here it's 95 in the summer and typically 10-15 in the winter.

    While I have you experts around, what do you think of the vacuum brake thing on the back of the Q-jet? Is it necessary? On mine it looks like under some conditions it restricts the choke and the secondaries, based on vacuum.
     
  9. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    [ QUOTE ]
    Well, I think I got it pretty close now. It seems like it was actually better the way it was, for the summer anyway (it wouldn't start i nwinter, I'm sure). Until the choke opens all the way, the engine is not real happy. Do you guys mostly wait a few minutes before driving away? I normally don't go instantly from starter to drive, but I haven't been waiting 3-5 minutes, or whatever it takes for the choke to open up all the way.

    Maybe a summer setting and a winter setting is in order? Around here it's 95 in the summer and typically 10-15 in the winter.

    While I have you experts around, what do you think of the vacuum brake thing on the back of the Q-jet? Is it necessary? On mine it looks like under some conditions it restricts the choke and the secondaries, based on vacuum.

    [/ QUOTE ]

    Leave the vacuum break alone. It's prupose is to get the secondaires shut down quick if you get off the gas. THis prevents a super rich condition and backfires through the exhaust on deceleration.
    The only thing I do leave off when I rebuild them is the secondary lock out lever that is controled by the choke. It's a little lever that blocks the secondary butterflies. I have had the trucks at angle and bouncing and had that thing swing into position and lock them out. Not fun where you climbing a steep hill and need all the mojo it has.

    I'm anal about letting them warm in the morning. I go out fire them up, go in fix my to go coffee cup then head out. After it sits all day I fire it up and smoke a cig (don't smoke in my burb because the kids ride in it).

    I intentionnaly ran extra choke in the wife's 79 to make sure it was cranky as all hell till it was warm. Telling her 100 times to let it warm did no good. She's a fire it up and thow it in gear before the starter stops spinning type. After flooding it out a few times she finnaly learned to let it warm a little. /forums/images/graemlins/rotfl.gif
     
  10. Mastiff

    Mastiff 1/2 ton status Premium Member

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    [ QUOTE ]
    The only thing I do leave off when I rebuild them is the secondary lock out lever that is controled by the choke. It's a little lever that blocks the secondary butterflies. I have had the trucks at angle and bouncing and had that thing swing into position and lock them out. Not fun where you climbing a steep hill and need all the mojo it has.

    [/ QUOTE ]

    The last guy who rebuilt mine had that tied up with a piece of wire. Not knowing what the point of that was, I put it back to normal. /forums/images/graemlins/grin.gif

    Is that how you disable it, tie it up with wire?

    Thanks!
     
  11. R72K5

    R72K5 Banned

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    well if you wire the lever so that it doesnt contact lockout then yeah youd pretty much be disabling that, keep the linkages on the carb lubricated and clean, carb cleaner and compressed air and then spray oil or similar to keep it all free moving.

    good luck
     

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