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Power Issue 4.7 v8 289 coupe

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    Power Issue 4.7 v8 289 coupe

    I was hoping people had some advice, I had a new 4 barrel carb and manifold fitted, new points and condenser, but when I getv up to about 30mph I just have no power. I have checked I am getting fuel to the carb, and that it is fully opening, was seeing if anyone had any knowledge I could tap into to help.

    many thanks

    #2
    Not easy to help much from afar.

    Was it good before your changes?

    What carb, cfm, vac or mechanical secondaries?

    Have you a good dial back timing light (will also show if the advance is working)

    I would bin all points/condenser setups for a pertronix or msd, obviously not if you're a purist/constant tinkerer.

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      #3
      As Richard says it is not easy from afar. Also you have changed both the carb and the ignition system at the same time.

      Was the car running good on the old (presumably) two barrel carb?

      What 4 barrel carb is fitted (Make and CFM)?

      Does the car idle ok?

      To be honest these aftermarket carbs run fairly good out of the box if fitted correctly. Sometimes they have a bit of a flat spot off idle and can go a bit lean at wide open throttle but this isn't difficult to dial out.
      Allan

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        #4
        Originally posted by Bradey View Post
        I was hoping people had some advice, I had a new 4 barrel carb and manifold fitted, new points and condenser, but when I getv up to about 30mph I just have no power. I have checked I am getting fuel to the carb, and that it is fully opening, was seeing if anyone had any knowledge I could tap into to help.

        many thanks
        best thing you could do is ditch the points and condenser set up and convert to petronix electronic ignition with 40000 volt coil which allows you to run up to 40 thou plug gaps done that set up on my 66 289 best upgrade I could have done

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          #5
          First up, I'd check the engine vacuum and if you don't know how to do that there are plenty of eBay sellers offering gauges and hosing and plenty of YouTube videos on Ford 289 vacuum tuning. You need to make sure you are pulling around 16 - 20" Hg. If its pulling a lot less than that then your timing is way out or you have engine issues of compression (or a vacuum leak); valve issues or ring issues. Once you have a good vacuum reading at tick over then you know the engine is good.

          I'd look then to the engine timing, if you have replaced the points then you should check the dwell angle and timing as a matter of course. Your timing would have to be a really long way out though to max out at 30mph. Probably around 20 degrees out.

          So once you know the engine is good and the timing is good then it is pointing to a fuel issue (if you have no misfiring its unlikely to be the ignition, that's not to say it couldn't be coil breakdown but that's way down the suspect list but it is an easy check if you have a spare coil sitting around), that'd either be a last legs fuel pump or pipe restriction causing fuel starvation or a problem with the carburettor metering or floats. Suspect the carb last because if it fires up and runs smoothly then that suggests the carb is doing its job and focus on possible fuel starvation, which would be the pump as first suspect. Although you know fuel is pumping a knackered pump will not give the required fuel volume to support rapid acceleration and high speed cruising.
          Last edited by rider; 05-07-2017, 04:34 PM.

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