68 383 with 750 carb. Runs rich

Discussion in 'Fuel and Air Systems' started by gdbuick, Jul 24, 2018.

  1. gdbuick

    gdbuick Active Member

    Messages:
    29
    Likes Received:
    1
    Joined:
    Oct 13, 2017
    Location:
    Boston
    Local Time:
    5:11 AM
    Hello
    I’m just finally able to start driving a car I picked up before winter. Just back from mini tub. It’s a 383 auto eldelbrock torker manifod with a Holley 3310 750 vacuum secondaries. 391 rear gears 3000 stall. It’s start right away cold but it’s is running rich with fumes. It seems to drive okay though. I did adjust the air/fuel screws to highest vacuum (about 12 inches car was in park) using a vacuum gauge but no effect on richness. I should have checked timing first as I don’t know where I’m at. The big issue above running rich is after a ten minute drive shutting off and trying to restart 1 hr 30 mins later it cranks away but won’t start (has happened four times now). It does eventually start and runs great except richness.
    When it didn’t start I did check spark and it was good. So I took apart the carb just now as I’m waiting for a rebuild kit. Is there a smoking gun I should look for inside? The jets were 72 and power valve stamped 6 5BF9BEBC-434C-4EA5-A0AE-C47D14E1FB0B.jpeg although it appears they had two gaskets on it. Got to love the fuel line routing to but hey it’s a father son project.
    Thanks
    Greg

    78F4E9B7-3BAB-4F3C-8F0C-45B4C41BE11F.jpeg
     
  2. Treblig

    Treblig FABO Gold Member FABO Gold Member

    Messages:
    4,440
    Likes Received:
    1262
    Joined:
    Oct 5, 2013
    Location:
    South Texas
    Local Time:
    4:11 AM
    The power valve number should be set by your idle vacuum number. The power valve should also be set by whether or not the car stumbles on acceleration. Also gasoline doesn't like "sparks"...I would move the coil!!

    treblig
     
  3. 383Scampman

    383Scampman Well-Known Member

    Messages:
    797
    Likes Received:
    182
    Joined:
    Nov 24, 2013
    Location:
    New Hampshire
    Local Time:
    5:11 AM
    Make sure your vacuum advance is working . If you don't have v.a., get one . Set your idle in gear . Depending on your camshaft , your initial timing should start about 5-7 Deg. Total timing about 32 degrees for todays gas . Start there, and for safety sake , move that fuel line .
     
  4. brian6pac

    brian6pac Well-Known Member

    Messages:
    2,435
    Likes Received:
    1105
    Joined:
    Nov 15, 2016
    Location:
    N.E.Ohio
    Local Time:
    5:11 AM
    I would put a 3.5 power valve in it, if you have 12 " in park it will go down in gear. Start there and see how it runs, also put a long hose on your vacuum gauge and watch it driving down the road and standing on the throttle.
     
  5. Locomotion

    Locomotion Well-Known Member

    Messages:
    2,630
    Likes Received:
    210
    Joined:
    May 31, 2004
    Location:
    Florida
    Local Time:
    5:11 AM
    Backfires can damage a power valve and cause it to run rich. Double-check the float level and new needle & seats. The 72 primary jets are original. The secondary plate is equal to 75 or 76 jets. They make a secondary block that can replace the plate so you can easily change secondary jetting.

    When going through a carb, I like to spray carb cleaner through every hole, especially the air bleeds (from the bowl side). Watch your eyes!

    You might be able to get a little more idle airflow by opening the secondaries a tiny bit with a screw located underneath near the vacuum pod. This is like drilling holes in the primaries. But that's usually tried with bigger cams.
     
    • Like Like x 1
    • B'cuda

      B'cuda Well-Known Member

      Messages:
      128
      Likes Received:
      56
      Joined:
      Feb 13, 2018
      Location:
      Newburg MD
      Local Time:
      5:11 AM
      Clean the air/fuel passages in the metering block with wire, compressed air, carb cleaner and goggles, If ethanol gas dried in it at any time. Once back together check Holley carb setting videos on YouTube. Accelerator pump, idle circuit etc.
       
    • brian6pac

      brian6pac Well-Known Member

      Messages:
      2,435
      Likes Received:
      1105
      Joined:
      Nov 15, 2016
      Location:
      N.E.Ohio
      Local Time:
      5:11 AM
      I would not worry about the fuel line or the coil, a good H.O. coil spark will jump 2-3" gap and Mopar didn't have a problem running the fuel line by the dist. Might want to make a fuel line out of steel and get rid of most of the rubber hose.
       
      Last edited: Jul 24, 2018
      • Agree Agree x 1
      • gdbuick

        gdbuick Active Member

        Messages:
        29
        Likes Received:
        1
        Joined:
        Oct 13, 2017
        Location:
        Boston
        Local Time:
        5:11 AM
        Thanks for the advice. Unless my power valve is shot I’m very confused what is happening after the car runs just a short time and sits for a about an hour it’s hard to start. Stone cold it fires right up.
         
      • brian6pac

        brian6pac Well-Known Member

        Messages:
        2,435
        Likes Received:
        1105
        Joined:
        Nov 15, 2016
        Location:
        N.E.Ohio
        Local Time:
        5:11 AM
        That is a old torquer that has heat going through it right? the fuel is boiling after it sits a while, you could try a insulating spacer if you have the room to clear the hood or get a valley pan that blocks off the heat, not sure they make them for a 383 they do for a 440.
         
        • Like Like x 1
        • Treblig

          Treblig FABO Gold Member FABO Gold Member

          Messages:
          4,440
          Likes Received:
          1262
          Joined:
          Oct 5, 2013
          Location:
          South Texas
          Local Time:
          4:11 AM
          If you let it sit for an hour after running for a while then before you try and start the engine pour some gas down the carb. If it fires up like normal you'll know that the gas is evaporating out of the carb. You might not know why the gas is evaporating but you'll know where you're problem lies.

          treblig
           
        • MOPAROFFICIAL

          MOPAROFFICIAL Well-Known Member

          Messages:
          2,040
          Likes Received:
          1063
          Joined:
          Jun 1, 2016
          Location:
          breakwater
          Local Time:
          2:11 AM
          Set your idle mixture with it in drive or reverse, have a friend sit in the car with their foot on the brake.

          Buy the meter block it loco recommended for easy jet changes. You want a power valve rated 2" below the vac reading you get in gear @idle .

          Rule of thumb for me, never use a vac sec carb with 3000+ stall converters, get a dbl pump with a 4 corner idle.
           
          • Like Like x 1
          • gdbuick

            gdbuick Active Member

            Messages:
            29
            Likes Received:
            1
            Joined:
            Oct 13, 2017
            Location:
            Boston
            Local Time:
            5:11 AM
            Thanks for more input. Wow never thought of the fuel boiling. Where this hard start is not an issue cold but only after just a short ten minute drive and then sitting for 1 to 1.5 hrs (gym time)that thought escaped me. I think my engine temp gauge was about 180 degrees on shut down only about 5 mile ride from house to gym. I'm not familiar with this manifold or mopar engines in general yet (wrenched on buick engines for 27 years). I bought this car as it is setup now and working out the bugs and obviously the fuel line setup with rubber hose from the fuel pump to carb especially with the fuel rail pointing towards the back is pretty ugly. I will clean up just the front metering block of the carb for now and put back together with new power valve. Sounds like I need to redo air/fuel with car in park too and then see what happens and follow some of the ideas above once she is running again.

            Edit - one thing that doesn't make sense to me yet is if the fuel is boiling off after a short drive and sit for 1-1.5 hrs. Then why if I take a drive and park in my garage overnight it starts right up next day without barely a touch of gas. Seems to me if it boiled away when parked in garage it would take some refilling of the carb before it started again next day.
             
            Last edited: Jul 25, 2018
          • Aaron65

            Aaron65 Well-Known Member

            Messages:
            456
            Likes Received:
            71
            Joined:
            Nov 16, 2013
            Location:
            Michigan
            Local Time:
            5:11 AM
            It's not necessarily that it's all boiling out of the bowl, it's that modern fuel expands very easily with heat. Most of the time it expands into the manifold through whatever passage is most convenient, and when it hits that hot manifold, it vaporizes. Therefore, when you go to start it hot, you have a pig rich mixture pumping through there until the engine can clear it out.

            Phenolic spacers can help, and adjusting your starting method can help. Crank it for a second with your foot off the gas, then slowly push your foot to the floor like you have a flooded engine (because you do). Make sure your choke unloader is working. Usually, the engine will catch within a couple seconds.
             
            • Agree Agree x 2
            • gdbuick

              gdbuick Active Member

              Messages:
              29
              Likes Received:
              1
              Joined:
              Oct 13, 2017
              Location:
              Boston
              Local Time:
              5:11 AM
              Ok, making more sense to me now. I failed to mention there is no choke hooked up to this car. When cold it always fires right up with little to no gas applied with pedal and stays running without feathering the gas pedal. When I was stuck I did try to hold pedal down to the floor but it didn’t seem to help any.
              After multiple attempts at starting the car at one point it gets where you can hear the engine Sputter a little and then next turn of key bam she is alive like nothing ever happened. When she was not starting I also did look down the carburetor and manually squirt gas using the throttle linkage to ensure I had fuel. I could also see gas in the clear gas filter. Thks Greg
               
            • gdbuick

              gdbuick Active Member

              Messages:
              29
              Likes Received:
              1
              Joined:
              Oct 13, 2017
              Location:
              Boston
              Local Time:
              5:11 AM
              Ok finally had a chance to put my carb back together. I did not rebuild the whole carb as the powervalve seemed suspect and had some build up around it. I installed a new power valve which came in kit as 6.5, new fuel pump diaphragm , pulled air/fuel needles and installed fresh cork seals for them and new gaskets coated with silicon spray lubricate for front block only. Also blue out all passages with carb cleaner and compressed air. Fuel float level was good before pulling apart. Didn’t take apart rear of my carb yet and didn’t realize the kit didn’t come with 2nd vacuum diaphragm parts which I’m not sure are working yet. Where I never checked timing originally I figured to take a look after assembling and see if anything changed. So car started right up with initial air/fuel at 1.5 turns out.
              Checked timing and was set at 10 BTDC and 35 degrees around 2400 ish with dist vacuum unplugged and capped off. I tweaked the idle timing to 15 BTDC.
              My original problem was a hard hot start I will need to drive the car to see if that is gone or not and the car is too rich and it still too rich. I did notice if I put the car in park or drive there is very little difference in vacuum Gauge readings. I also sprayed around with carb cleaner trying to find a vacuum leak I didn’t. I also put both my hands over the carburetor with welding gloves and it seem the engine could just keep on running. Unfortunately I did not have a helper to put it in drive to adjust air fuel. When in park my highest vacuum reading is with the air mixture screwed all the way in, this does not seem right to me almost like I have a vacuum leak. Both sides react the same. Current vacuum around 12 at idle and 15 ish air/fuel all the way in.
               
            • DJC

              DJC Well-Known Member

              Messages:
              211
              Likes Received:
              33
              Joined:
              Sep 6, 2012
              Location:
              Chilliwack, BC, Canada
              View My Photos
              Local Time:
              2:11 AM
              Mine Holley was rich as well, changing the power valve mad a great difference. From Holley Power Valve Tuning - Holley Blog:


              "High Performance Engine Power Valve Selection:
              High performance engines with modified cylinder heads, long duration camshafts and single plane intake manifolds may require a change to the power valve. To find out which power valve your high-performance engine needs, you can perform the following procedure:

              1) Hook a vacuum gauge to an intake manifold vacuum port.


              2) Warm up the engine and note the vacuum reading at idle. Automatic transmission vehicles need to be in the Drive position, while manual transmission vehicles can be in Neutral.


              3) Divide the vacuum reading in half. The number will determine the correct power valve.


              Each power valve is stamped with a number that indicates the correct vacuum opening point. For example a power valve with the number #65 stamped on it, will open at 6.5 inches of engine vacuum. As an example, a vacuum reading at idle of 13-inches, is divided by two and results in a 6.5 inches of vacuum. Therefore, you should have a #65 Holley Power Valve installed in the carburetor.


              If you divide the vacuum reading and it falls on an even number, you should select he next lowest power valve number. For example a vacuum reading of 8-inches, divided by 2 and you come up with a number of 4. In this case you would use a #35 power valve.

              Finally, if your engine produces 13 inches of vacuum or more, the stock power valve that the carburetor is equipped with from the factory, is sufficient.


              Holley power valves come in a range of orifice sizes. The higher the number the more fuel is added."
               
            • mopowers

              mopowers Well-Known Member

              Messages:
              3,610
              Likes Received:
              797
              Joined:
              Feb 15, 2006
              Location:
              West Sacramento, CA
              Local Time:
              2:11 AM
              How is this true? I always thought the amount of fuel flowing through the PV circuit is determined by the PV channel restricters.
               
              • Like Like x 1
              • DJC

                DJC Well-Known Member

                Messages:
                211
                Likes Received:
                33
                Joined:
                Sep 6, 2012
                Location:
                Chilliwack, BC, Canada
                View My Photos
                Local Time:
                2:11 AM
                Perhaps it means more total through the carb...?
                 
              • Locomotion

                Locomotion Well-Known Member

                Messages:
                2,630
                Likes Received:
                210
                Joined:
                May 31, 2004
                Location:
                Florida
                Local Time:
                5:11 AM
                The power valve is simply an on/off switch. The # determines at what vacuum level that "switch" opens. (i.e.: 6.5") The amount of fuel flow is determined by the size of the 2 little holes under the power valve - PVCR (power valve channel restrictions)

                There are several theories as to what power valve will suit your needs and variables in the vehicle. Needs/applications vary. So the power valve opening formula may be different for a drag car as compared to a street car. In some cases, the power valve is removed and jetting sized raised to compensate. The bigger the PVCR, the larger the jet size is needed to compensate when the power valve is removed & blocked off.
                 
                Last edited: Aug 3, 2018
              • AJ/FormS

                AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

                Messages:
                13,385
                Likes Received:
                3124
                Joined:
                Jan 19, 2014
                Location:
                South-Central Manitoba,Canada, 900ftelevation
                View My Photos
                Local Time:
                4:11 AM
                That fuel supply line is a recipe for disaster.
                First is the multiple gear clamps, that do not provide proper 360 degree clamping,
                Second is the glass multi-piece filter,
                Third is the soft lines.
                How many failure points are there? I count 6 in that picture, including the glass filter sitting on top of the heat crossover passage. You only need one to burn your car down.
                The boiling point of the lightest components of gasoline is ~95*F. In all likelyhood your carb will run hotter than that. Your fuelpump may be hotter than that. The fuel in your rubber line may be hotter than that. If just one of those 5 possible failure points, fails, the fuel may not even come out as a visible liquid. And as a vapor, it only needs a tiny spark to flash.

                Oh, and just because the factory put the coil there, does that mean it's the best place for it?
                Smelling gas fumes, with the engine running, is NOT normal,and probably dangerous.
                I don't see an operational PCV system.
                At some point, you're gonna want to hook up the vacuum advance, to that currently capped sparkport, but right now it has nothing to do with your hard hot-start.
                Is that a 6-cylinder throttle cable? It looks a little long and is operating at a pretty severe angle where it exits the firewall; One would hope it never sticks at WOT
                I'm not picking on you or your combo; I just care enough about somebody's hard work and time, getting it to where it is today, and enough about you to not see your dream possibly destroyed , possibly with you and a loved one(s) still in it.
                 
                Last edited: Aug 4, 2018
                • Agree Agree x 1
                • gdbuick

                  gdbuick Active Member

                  Messages:
                  29
                  Likes Received:
                  1
                  Joined:
                  Oct 13, 2017
                  Location:
                  Boston
                  Local Time:
                  5:11 AM
                  Thank you for the comments. I didn’t set up this car (bought as is)and want to make it safe and correctly running. The is my first Mopar so I am learning. I agree on the gas lines and coil placement, Mopar was not the only one to mount coil’s right by the carb. I need to do more work on the gas line but I did correct some of it when I had the carb off. Funny found the gas filter inside the glass case is Missing. My finger is pointing where the vacuum advance is currently connected is this not correct ?
                  I am not sure where a PVC system is supposed to go. The back of the carb large port is capped off.
                  Good point on the accelerator cable I don’t know if that’s a six-cylinder or eight but I agree it has a nasty curve to it.
                  You don’t smell raw fuel it’s more just a really rich smell out the exhaust not so bad after carb work And the 5° more initial advance. No hot start issues yet but it’s early to tell it was intermittent.

                  I think a replacement air cleaner set up needs figured out too. Keep the suggestions coming I want to fix this and my valve covers leak oil badly. I changed out the gaskets with no luck had to redo them with RTV for now, ugg.

                  F571EA9A-5B02-4487-88FD-2B6A801738BE.jpeg

                  2377567B-EEDB-4495-8939-BAC9301FF901.jpeg

                  F1D7AA6A-4E3D-4797-A367-35BC9DE74CAA.jpeg

                  1F72C2F4-4CE2-486B-A0AD-52DD661B318F.jpeg

                  6306FF26-1EDC-462D-8A69-F796C0089483.jpeg

                  238C5621-C81B-40FB-9D94-0B550CB050AF.jpeg

                  E8D7EA65-7ECB-4041-B063-5E3A87970167.jpeg
                   
                • gdbuick

                  gdbuick Active Member

                  Messages:
                  29
                  Likes Received:
                  1
                  Joined:
                  Oct 13, 2017
                  Location:
                  Boston
                  Local Time:
                  5:11 AM
                  Please don’t pick on fan shroud setup (came with the car)That’s ugly and scary, better than nothing I suppose but the fan blades are exposed when using timing light. I plan to ditch that whole set up for another quality aluminum radiator with electric fans during the winter.
                  Also note I have no idea on the condition of this motor. I’m pretty sure it’s just a used motor he bought from somebody and threw into the car (although I was told it was rebuilt I have my doubts now). I’m just trying to get it sorted out for now so we can drive it. My son and I have not driven this car more than 200 miles since owning it. We plan another 383 or 400 combo in it.
                   
                • Locomotion

                  Locomotion Well-Known Member

                  Messages:
                  2,630
                  Likes Received:
                  210
                  Joined:
                  May 31, 2004
                  Location:
                  Florida
                  Local Time:
                  5:11 AM
                  I can't really tell from the pics, but as far as the oil leak is concerned, make sure that the valve cover lips aren't touching the intake manifold. In many cases, at least on small blocks, cast valve covers and/or the intake port tops need to be relieved to avoid contact.

                  Put the valve covers on a flat surface and check for "rock" or spaces to see if they may be warped.
                   
                  • Agree Agree x 2
                  • AJ/FormS

                    AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

                    Messages:
                    13,385
                    Likes Received:
                    3124
                    Joined:
                    Jan 19, 2014
                    Location:
                    South-Central Manitoba,Canada, 900ftelevation
                    View My Photos
                    Local Time:
                    4:11 AM
                    Comments inside the quote, in blue
                    OK with the additional pics, I see that you do not have a working PCV; get that fixed before anything else is attempted, because it affects everything except the power timing.
                    PS I love the color of your Dart.
                    And I could live with that shroud no problem, and for sure I would not install electrics to ditch it. I think it adds a tough-guy look to your underhood,lol.
                    And those valve covers are probably the best kind you could have. As already mentioned, check for interference between them and the aluminum intake runners. Most of the time these covers are used, they have to be notched at the runners to make room for them.
                    And now for the really big deal
                    Check your idle timing with and without your vacuum advance hooked up. I think you have your can hooked to full-time manifold vacuum. The Vcans are able to add from about 9 to 22 degrees at your 15* of idle vacuum. If you run it this way with 15* of initial, your total idle timing could end up being 24 to 37*, and the only way to slow the engine down would be to back out the speed screw......... which would kill the transfer port exposure.
                    Now riddle me this; if you shut off the transfers,With no PCV idle bypass air, what is the engine supposed to idle on? And how is it supposed to be able to hot-start?
                    When you get everything working again, you should be able to hot-start it with just a twist of the key; click-vroom.

                    So to recap
                    Install a PCV system,
                    Make sure your breather breathes in both directions.
                    Close up the secondaries.
                    Set the T-port exposure to square to a bit longer than wide.
                    Reset the mixture screws to 3/4 turn.
                    Replumb your Vcan to the spark-port.
                    Start it up and;
                    >Reset the idle-timing to 10degrees.
                    >Verify that the Sparkport has less than 4inches of vacuum on it at idle, preferably ZERO inches vacuum. And that the vacuum there rises with rpm.
                    >Fine tune the idle speed to about 700/750rpm, using a combination of speed screw adjustment in the range of +/- .5 turns from the initial T-port exposure setting, and the rest with idle-timing.
                    >Reset the idle quality with the mixture screws in the range of .5 to 1.5 turns from lightly seated.
                    > The idle fuel,(the mixture screws)and part throttle fuel ( the transfer ports), comprise the low-speed circuit, together with the float level adjustment and the Idle-Air-bleeds. When you dink around with the Idle-timing and try to maintain a proper idle speed, this messes up the low-speed fuel delivery system. With a 3000TC there is no reason to run a lot of initial timing. Get this sorted and then if you like you can whack the timing in with lightweight springs in the Distributor.
                    Setting the idle speed fuel is a balancing act between the mixture screws and the Transfer port exposure. In most cases, and like yours where the idle vacuum is quite high, having the mixture screws set to between .75 turn and 1.25 turns, and the exact right amount of transfer exposure, will yield the best idle, the best off idle and the best Tip-in response without a lot of help from the accelerator pump.Let the idle timing fall where ever it wants to; between 10 and about 18 degrees, to get an idle in the range of 700 to 750. At this stage I wouldn't bother with trying to maximize idle vacuum, or idle AFR, or Idle-timing; you cam mess with that at some later date, after you have a good-working base tune in her.
                    The mainjets will not affect this part of the tune; you could take 'em right out with no change in the idle. And as long as the PV is not ruptured, it will not affect the idle/low speed circuit either; you could block it right off without it affecting the idle/off-idle at all.
                    But the float level is a BIG,BIG, player in this circuit. Saying it is good is somewhat vague. Saying it is set to the factory spec is the proper answer.
                    > forget about the vacuum gauge as an idle speed tuning tool. You can however install it, and read it, and use it for a diagnostic tool, for all other purposes.
                    Happy HotRodding
                     
                    Last edited: Aug 5, 2018
                  • Mattax

                    Mattax Just the facts, ma'am FABO Gold Member

                    Messages:
                    2,590
                    Likes Received:
                    1104
                    Joined:
                    Feb 7, 2013
                    Location:
                    Phila. Pa
                    Local Time:
                    5:11 AM
                    Install the filter so the outlet is higher than the inlet. This helps vapor bubbles burp get out through the carb bowls when the inlet opens. Sometimes a vapor bubble will actually push some fuel ahead of it. If it grows while the bowl inlets are closed, it can have pressures higher equal to the pump outlet. These are all variations on vapor lock.
                    I've had vapor lock situations on the suction side of the pump - that's even worse. When this happens while driving you'll smell fumes and the carb will seem to run out of fuel and then iusually recover when you let off the gas and slow down.

                    Underneath is a manifold vacuum port. Whether its correct or not depends on engine and the mechanical advance. One situation you can use it when engine has strong idle vacuum, the advance curve is long and the initial timing is close to TDC (Say 0* to 5* BTDC at 600 - 750 rpm). If using 10 -15* BTDC on a stock 383, or more if its got some cam, then use the ported vacuum.
                    Regardless. Always set initial timing with vacuum plugged.

                    On the v-8s, there is also a difference in cable lengths depending on whether a dual plane or single plane manifold was used. A bunch of the 2 bbls 273 for example used a single plane. Just something else to look out for when hunting for one with a shorter length.

                    If it starts easily when cold and the choke is not being used, then its prob too rich at idle.

                    IMO they're another can of worms. There's no inherent advantage (OK there is a few HP) and there's the matter of wiring them into a system design that wasn't intended to have extra equipment running with the engine off. Its doable, but more work and the electrical system needs to be thought out and executed well.
                     
                    Last edited: Aug 5, 2018
                    • Agree Agree x 1