New to the AFB

Discussion in 'Carter' started by FormerGNowner, Nov 26, 2013.

  1. FormerGNowner

    FormerGNowner Well-Known Member

    Need some help with the choke on the Skylark. If it sits long enough for the carb bowl to dry out, it takes for-frickin-ever to get it running. A couple of pumps will usually get it to kick over, but then it's literally 2 minutes of crank-catch-feather the gas-stumble-die-rinse-repeat. I haven't found anything in the linkage that's bound up or falling off.

    The dial was about four notches towards lean when I got the car. It's now back to the centerline, but no real difference.

    The second pic shows a length of vac hose that goes nowhere. (it's on the air cleaner stud just as a visual) It's above the bowl, so I assume that it's just a vent, but I'm open to answers.

    Question 1: Where's a good place to start with tuning the choke?
    Question 2: What's up with the 12" vac line to nowhere?

    Thanks guys.
    Loren
     

    Attached Files:

  2. wkillgs

    wkillgs Gold Level Contributor

    Adjust the choke so it almost closes when it's cold.
    There should be a metal tube running from the choke to the exhaust manifold.... it will supply hot air to the choke, making it open as it warms up. The vacuum hose attaches to the other end of the exhaust manifold heat tube, it's purpose is to supply filtered air to the choke.
    An aftermarket electric choke would be an option.
    The best cure for the dry carb issue is to use a squirt bottle to fill the carb bowls through the vent tubes. Or install an electric fuel pump.
     
  3. FormerGNowner

    FormerGNowner Well-Known Member

    I have an aluminum tube than runs down to the exhaust, near the firewall. I think we're good there.
    I guess I'm being dense about the vac line from the carb to the choke. Should the brass nut on the front of the choke actually be a tee, or am I not seeing the empty tube that the hose ought to run to?

    Thanks.
     
  4. wkillgs

    wkillgs Gold Level Contributor

    There's a tube that goes through the exhaust manifold. One end goes up to the choke housing (the alum tube you mentioned). The other end should be connected to a tube that goes up the back of the engine and attaches to the vacuum hose you mentioned. You might be missing that tube. You can make one from some brake line tubing. there might be pics in the shop manual.
     
  5. FormerGNowner

    FormerGNowner Well-Known Member

    OK. Need see what's hiding (or not) on the back of the engine. I'll check the manual for vac routings rather than the carb drawings.

    I'll post an additional picture, but it seems like the alum tube ought to be close to the exh manifold if it's moving warm air to the choke. Mine's off in space away from anything that would keep it warm.


    Thanks for your help.
     
  6. FormerGNowner

    FormerGNowner Well-Known Member

    I think it's clearer now. There's no clean air tube internal to the exh manifold (this was originally a 2bbl car, I can't even say for sure if these are '65 manifolds).

    If that tube were present, I'd come from the carb to the aft/bottom end of the manifold. At the front/top end of the manifold would be a short piece from the warm tube up to the choke. As it is right now, I'm pumping exhaust to the choke, not filtered air from the top of the carb.

    Am I on the right track?
     

    Attached Files:

  7. wkillgs

    wkillgs Gold Level Contributor

    There should be a short piece of stainless tubing that passes thru the manifold. It's open at both ends, and there should be no exhaust entering the tube. The line from the choke should slip into the front of the tube, and the line from the top of the carb should slip into the back.

    Airflow should be as follows... filtered air enters at the top of the carb, flows thru the line to the rear of tube in the manifold. There, it is heated and comes out the front of the manifold tube, thru the line to the choke housing. The heated air makes the choke coil/spring expand, closing the choke flap. There is a small vacuum passage between the choke housing and the carb throat... this vacuum is what pulls air thru the line. It's common for this vacuum passage to be clogged with crud. I'd guess you could take the line off of the choke housing and feel a vacuum at the housing.

    Your setup has the line to the choke at the rear of the manifold, it should be at the front.

    Here's a pic I have on file of my '66 300. It somewhat gives you an idea of the routing. The rear line is the rusty one. Looks like the front line connects midway on the manifold, I'll have to look later. 300 choke tube.jpg
     
  8. bnam

    bnam Well-Known Member

    That hose connects to the tube that goes into the back of the exh manifold.
    IMG_3398.jpg

    IMG_3399.jpg
     
  9. FormerGNowner

    FormerGNowner Well-Known Member

    Thanks bnam. I've got some plumbing to correct.
     
  10. FormerGNowner

    FormerGNowner Well-Known Member

    Plumbing fixed and things are much improved. Thanks for the direction guys!
     

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