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2F Carb - desmogged vacuum routing

Discussion in '40- & 55-Series Tech' started by Bostonfj60, Dec 13, 2009.

  1. Bostonfj60

    Bostonfj60 New Member

    Messages:
    399
    Location:
    Natick, Ma
    I just finished putting the header on the 40. The truck was 80% desmoged when I got it, so I just finished it up.
    The only thing left was basically part of the EGR system. All the vacuum lines, ect had been pulled, and the associated vacuum ports on the carb were capped.

    I attached a diagram that has a number of things marked. My main question has to do with the two vacuum lines that run from the distributor and to the carb (the vacuum advance). I thought on my 60 the two vacuum advance lines were attached to the carb itself (possibly in port 1 and 2) and NOT to the air cleaner itself. Before I did the header, the truck had good power, but idled very rough, especially when it warmed up.

    I also recall at least one vacuum line going from 4 to somewhere on the carb (on my FJ60)
    and what is 5?

    So, please make comments on my diagram...anything at all that does or does NOT look right to you.

    Thanks !

    Attached Files:

    • carb.jpg
      carb.jpg
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  2. Rocky_LC

    Rocky_LC SILVER Star

    Messages:
    1,432
    Location:
    Tucson, AZ
  3. homebuiltcruiser

    homebuiltcruiser Regular Member

    Messages:
    137
    Location:
    Wall Township, NJ
    old thread

    You may want more than this, but maybe it will help

    http://forum.ih8mud.com/40-55-series-tech/290314-78-running-rich-carb-setup.html

    The post on this from fj40jim gave great directions on the bare minimum of what I needed. Basically, all I have routed is the distrutor advance straight to the carb and the brake booster. Runs great.

    In random order:
    Remove the 2 screws and flip the Hot Idle Compensator rightside-up. Connect HIC top fitting to the blue capped breather fitting. Connect HIC lower fitting to vac port on carb insulator base. Ignore the 3 small vacuum connections.

    Cap off other larger vac fitting in the side of carb insulator base since there is no canister purge hose to connect to it.

    Remove & discard Carb Temp Sensor (CTS). There is nothing to hook it to now.

    There is the remnant of a manifold Vac (VAC) fitting in the top of the intake just ahead of the carb. It should be capped or removed & plugged.

    Show us a pic of the dissy. It should not have a condensor because it is fully electronic. It may be a points dissy w/ vac retard or advance.

    Dissy vac is routed off the wrong port. It should come from one of the ported vac(PORT) ports, not the Throttle Positioner port.

    For now, the CB should be connected to the TP port.

    Cap off the Power Brake booster fitting on the back of the intake. Better yet, get some booster vac vose and connect the PB booster to the PB manifold fitting.

    Connect the PCV hose to the PCV fitting on the side of the intake manifold.

    Connect the carb Evap port to the canister valve. If there is no canister, then cap the carb port.

    Pics may help:
    Attached Images[​IMG] [​IMG]
  4. 1911

    1911 chupacabra SILVER Star

    Messages:
    3,150
    Location:
    Parker County, Texas
    There is no vacuum at the air cleaner; the main advance from the distributor needs to go to the advancer port on the engine side of the carb. The "high altitude" secondary vacuum does go to the air cleaner.
  5. Bostonfj60

    Bostonfj60 New Member

    Messages:
    399
    Location:
    Natick, Ma
    Great, thanks for all the words and resources!
  6. numby

    numby New Member

    Messages:
    743
    I'm not real familiar with 80's Cruiser stuff (or 70's or 60's for that matter) but the distributor advance (actually a dual advance) would normally be connected to two of the three ports on the rear of the carb. These carb ports are not arranged in a logical manner so you'll need someone else to identify them for you.

    The advance port on the dizzy that pulls in the most advance (pull the cap and apply vacuum to the advance nipples so you can watch the rotor) would be connected the carb port lowest in the venturi for the most "ported" vacuum. The lesser vacuum advance nipple on the distributor usually gets hooked up to the EGR port on the rear of the carb. This is also a ported source for vacuum but sits higher in the throat of the venturi and so comes in later in the opening of the throttle. I'd leave that one capped without advice from Jim C. or Mark to do otherwise. The third port on the rear of the carb is manifold vacuum and probably no longer needed. The vacuum advance nipples on the distributor do not connect to the air cleaner in a desmogged engine AFAIK.

    Number 4 supplies (filtered) manifold vacuum to the ABV if I remember correctly. Not needed anymore so leave it capped.

    Number 5 is the HIC ((hot idle compensator). The top of which probably goes to #3 and the bottom comes from a manifold vacuum source on the intake manifold. Again, I'd look for confirmation from a professional.

    I hope I'm not giving you too much crazy info. Good luck!

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