Just purchased a '67 Coronet 440, and it's slow...

Fuel and Air Systems

  1. old guys rule

    old guys rule Well-Known Member

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    If it is a 440 manifold there's your problem. It has to be sucking air and oil into the cylinders from the valley. Forget your plugs see if they're only. Take your carb off look inside the manifold for oil. If there's oil in the manifold get rid of it and get a 383 that is a low deck put it on and put the car back on. The carb is not too big it is a spread bore with tiny primaries. Vacuum secondary is only going to allow the engine to pull as much fuel and air as the engine needs in no more. Change the manifold for the right one put it back together and you will probably be fine.
     
  2. diesel_lv

    diesel_lv Well-Known Member

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    Please stay away from that engine until you read up on it. It is a 383 that was a 2bbl, hydraulic flat tappet, no adjustments.
     
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    • diesel_lv

      diesel_lv Well-Known Member

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      Read through the posts, the correct manifold has already been determined.
       
    • 747mopar

      747mopar FBBO Gold Member FBBO Gold Member

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      Go through the steps..

      #1 compression test because nothing will help if it doesn't have good compression.

      #2 ignition timing

      #3 carb tuning

      You can Google and find all of the specs or order a copy of the factory service manual but more often then not trial and error usually finds the best settings.

      The amount of performance gains to be found through proper tuning can make a HUGE difference. I went through this on mine, started off with a Mallory distributor with a one size fits all setting.. after a week of trying different things it went from being a slug off the line to being a tire shredder. Same with my first carb, couple days of jetting, power valve swaps etc and it started pulling hard through the rpm range.
       
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      • RJRENTON

        RJRENTON FBBO Gold Member FBBO Gold Member

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        IMO....
        The Dodge 440 is a model description not the engine size. IF the engine, as you noted, is in fact a 383 with a 2 bbl carb, then the intake manifold with the Rochester Q-jet, is likely from a '73 or '74 400 B block engine with a Carter Thermoquad carb.
        Depending on how much origionality you desire, then retire all your present stuff....manifold, carb and all the shoemaker adaptors stuff including the rubber fuel line and opt for what Mopar installed origionally. The origional carb was a Carter AFB, and minimal emission control devices. If interested, I can provide thd original AFB number. The Qjet number you noted # 17086046 and the model M4MEA was an electronically controlled step up piston unit.....not necessarily on the 4.3 L engine or ????. Its no wonder why is running poorly. Just my opinion of course.
        BOB RENTON
         
      • Don Frelier

        Don Frelier FBBO Gold Member FBBO Gold Member

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        If it was a 2 barrel then it wasn't an AFB.
        (Aluminum Four Barrell)
        But again a COMPRESSION test first
         
      • diesel_lv

        diesel_lv Well-Known Member

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        Why is everyone going round n round on "if" it was a 2bbl n what intake. That part was resolved early on. The 383 was originally a 2bbl. The intake is now a TQ 4bbl from a '75-'77 400 with a non original TQ on it.
         
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        • Don Frelier

          Don Frelier FBBO Gold Member FBBO Gold Member

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          That wasn't my point really...
           
        • chillbill

          chillbill Active Member

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          Ok so here’s the bad news: all cylinders reported 130-140 except cylinder 5, which was at 60. I tested it multiple times and it came back the same.
          I put some oil in there and that changed the pressure to about 70.
          I haven’t inspected the valve springs and rockers yet.

          Oh and all the spark plugs looked in great shape.
           
          Last edited: Jun 28, 2021
        • chillbill

          chillbill Active Member

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          I checked the stamping on the head: it looks like 2406518. Those are supposed to be the max wedge heads.
          But realistically, it’s probably a 516.

          I took off the rocker cover and took a quick look. Nothing seems out of place or obviously damaged/bad. Should I attempt to take off the springs and check the valve guides? Or better to take whole head off?
           
        • Kern Dog

          Kern Dog FBBO Gold Member FBBO Gold Member

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          Supposed to be Max Wedge heads?

          1 huh 2.png

          Uhhh....

          1 laugh 4X.jpg

          No. Max Wedge heads were never fitted to a 440.
           
        • BSB67

          BSB67 Well-Known Member

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          Probably this. The head will need to come off if you want to repair the low cylinder pressure.

          But it might be worthwhile to now determine the source of the low cylinder pressure. If you add compressed air to the cylinder, similar to conducting a leak down test, you may asertain if it is rings or valves, and which valve. This way you'll know now if it is a motor rebuild or just cylinder heads.
           
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          • Don Frelier

            Don Frelier FBBO Gold Member FBBO Gold Member

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            Cam lobes are good?
             
          • chillbill

            chillbill Active Member

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            No idea. How do I check that?
             
          • Don Frelier

            Don Frelier FBBO Gold Member FBBO Gold Member

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            A dial indicator on the rocker. Turn the motor over with a bar. Compare with another cylinder.
             
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            • a440ron

              a440ron New Member

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              I just read this thread. It sounded from your description of the problem that it's not even performing up to par for how it's equipped. A restricted fuel filter was already mentioned and I believe you replaced the inline filter. Did you know the quadrajet carb originally came with a small paper type filter in the inlet fitting? If you haven't already, you might check for it's presence. They are normally removed when an inline filter is installed but maybe it wasn't. Sounds like the previous owner had rust/debris issues hence the tank/fuel line replacement. You said above 30 mph the car reduced acceleration. Without driving it I can't say for sure if it's a fuel, ignition problem, etc. but usually a fuel starvation issue will get worse the faster you go probably to the point of dying. When letting up on the throttle a little it will usually pick up rpm's. Other fuel starvation problems could be a restricted "sock"/ strainer in the fuel tank, (attached to the sending unit), a kinked line, fuel pump problem, trash in carb, etc.
              A word of caution....be careful when removing and reinstalling the fuel inlet fitting on the carb. They are notorious for galling or stripping the threads. Be sure and don't crossthread it. You didn't say what your fuel leak was but that could be it. They used to make fittings to repair them but if that's the case you might consider replacing the carb. They do make adapters to convert a spreadbore intake to a squarebore if you have the hood clearance.
              There were many good comments in this thread about improving performance. With 60 psi on one of the cylinders it will never run to it's full potential. That should be addressed but just thinking you have more problems than that. Yes a rear end gear change would make a HUGE difference if you have the 2:76's. Best of luck!
               
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              • chillbill

                chillbill Active Member

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                This is where the leak was. I think the PO epoxied this just before selling the car and didn't clean it. It was much worse when I got it, but I cleaned it up a week ago and it's almost dry.

                The fuel inlet says FILTER with an arrow. Is the paper filter supposed to be in there?

                LFn469p1v3WKFfp1uhJJ8Mqaez4ySwLCdaRjcWfZZtLW0nelwSarBnBLcnunJCTYTrn4QfGlDqIw=s1896-no?authuser=1.jpg
                 
              • Don Frelier

                Don Frelier FBBO Gold Member FBBO Gold Member

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                One dead cylinder is about a 25% power loss.
                That needs to be top priority.
                I wouldn't spend any time on that carbeurator.
                 
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                • a440ron

                  a440ron New Member

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                  Yep that would be where it is if someone hasn't already removed it. There was a filter and spring in there from the factory. No harm in leaving these out as long as you have the inline filter. Just hoping for your sake it's still there and restricted. The leak issue at the plug someone epoxied isn't uncommon for a Quadrajet. I used to rebuild a lot of these back in the day. Normally taking a small hammer and peening (flattening) the lead around the outside of the plug would fix it but using quick set epoxy was also a common thing. Yes it needs to be clean!
                   
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                  • chillbill

                    chillbill Active Member

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                    I’m talking to local shops now. Hopefully will get it sorted in a couple of weeks.
                     
                    Last edited: Jul 2, 2021
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