Slant 6- Idle and Running

Slant 6 Engines

  1. nitro_rat

    nitro_rat FABO Gold Member FABO Gold Member

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    I see points, car is a '74?
     
  2. Silum

    Silum Active Member

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    Tested various things...

    Here is a video and photos. https://photos.app.goo.gl/gn1vTHGx7Rx93haW6

    The video shows the timing mark moving. I tested my timing light, it is working fine on my 4.7 and my wifes car. My damper can't be moving as it wouldn't be lined up to tdc every time right? The video shows it moving but it looks wierd because the shutter speed of the angle. The strange thing... the moving slowed down a little after everything I've done... weird!

    Distributor: Gear looks fine, is engaged fine. See photos
    hDNY0-sqpCGUfKpreWnALDR4V_0w-evp82NG_UMO8mQs-TOP3UJ15TrHQHpQj11x7xtFOXiA=w711-h947-no?authuser=0.jpg

    RustyRatRod mentioned the hot air valve (heat riser?). I looked at this and it does indeed appear seized. I have bashed it and WD-40'd the crap out of it, maybe I can get it unseized. Unfortunately if it is seized closed that would mean it would be harder starting, if it's seized open then its operating as it should at temp. Either way the car should run when warm. Someone is welcome to correct me if I'm wrong on that, I'll keep trying to get it unseized regardless, I also have a lot of oil or gas where the intake meets the exhaust manifold.

    I'll move on to testing vacuum pressures next and look for something hidden disconnected, ill try the cardboard trick too.
     
  3. KosmicKuda

    KosmicKuda FABO Gold Member FABO Gold Member

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    Yep, that heat riser shaft is definitely frozen.

    People think WD 40 is a cure for everything but even though it smells good, it is not a rust penetrant. WD stands for Water Displacement and was the 40th formula tried.
    For decades Mopar service manuals said to lubricate heat risers with their special lube. It is a secret formula penetrant/lubricant. I bought some on Amazon a couple years ago after SSD posted a link.
     
  4. Silum

    Silum Active Member

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    Could the heat riser be related to my problems of not starting warm... Maybe stuck open and heating the intake, the fuel and the carb?

    It is meant to be closed at temp?
     
  5. 1963dartgt

    1963dartgt FABO Gold Member FABO Gold Member

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    And a drool tube head,its a confusing hodge podge of slant parts...slantenstein.
     
  6. Silum

    Silum Active Member

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    That's because it's a 72 car, not a 74
     
  7. BillGrissom

    BillGrissom Well-Known Member

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    Good luck w/ your Holley 1920. My 1969 Dart idled poorly for decades, and it didn't have the complications of your later engine. I tried 2 rebuilt carbs, plus tried rebuilding them myself. After I changed to a whole new long block, and same thing, I tried a 4th carb (from Carquest I recall) and it ran like a kitten. All the others ran lean at idle. I think the problem is there is a sealed metering block for the idle circuit which gets clogged and most rebuilders don't touch it. Some guys here say they know how to blow one clean on an assembled carb by applying shop air to a hole in the base or throat (forgot). My 1964 Valiant slant came with a Carter BBS. That engine idles so smooth you can barely hear the engine is running with traffic going by. I also hated the side bowl on the Holley which can leak fuel and gaskets can be a pain. Overall, I would say the 1920 was designed to be ultra-cheap. Other manufacturers used it too. Many here say the later Holley 1945 is better (never tried). Another idea is the special Holley Economaster after-market they sold ~1980 to improve mileage. I recall a slant version. You occasionally see them on ebay. A harder option is to change to a 4 bbl intake (Offy or Edelbrock) and find a rare 390 cfm carburetor.

    Another thing I should have known at the time was about the choke pull-off at the top. Insure the diaphragm isn't torn. Push the stem in, block the vac supply tube w/ your finger and see if the stem stays in. The choke should be set to fully close when cold. As soon as the engine fires and builds vacuum, the pull-off should pop the choke open just slightly (1/8" drill bit). Mine was bad, so I always had to fuss with the choke adjustment summer to winter. They go bad because people spray carb cleaner on them, or get a little gas in them.

    After fixing the fuel issue, I suggest considering an electronic ignition upgrade. Points are a maintenance pain, tricky to adjust, especially in the dark grub zone of a slant, and give a weaker spark. I had a Crane XR700 optical retrofit in my 1969 for years, but outdated now. Pertronix is similar and Ignitor II better (no ballast). In my 1964 slant, I installed an e-distributor which triggers a GM 8-pin HEI module and their coil. Too bad nobody makes a ready-to-run HEI distributor for the slant, as they do for SB and BB. I bought one for only $45 for my 273.
     
    Last edited: Jun 26, 2020
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    • RustyRatRod

      RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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      WD40 is useless in that capacity. It's not penetrating oil. In fact, it's not even a lubricant. Try Sea Foam Deep Creep.
       
    • Silum

      Silum Active Member

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      Thank you for your reply BillG. I blew out every orifice with air during my rebuild but I also found some pretty badly damaged parts during the rebuild too. It's interesting seeing the full history of someone going through all the carb problems. I hear that the reman ones are awful so I figured I didn't want to waste my money on them. pishta is coming to the rescue and offering some parts for me to isolate if it really is my carb (I think it is!).

      For the choke, I'll check how close to 1/8th it is. I have probably sprayed carb cleaner on it a couple times by this point.

      For the timing, it's almost comical watching what it is doing and im still not ruling out my timing light, even if it works on other cars. I see no other way to explain it.
       
    • Silum

      Silum Active Member

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      Yes I know this story, except for their penetrate version. For something that doesn't penetrate or lubricate, it does a surprising job at both though (the multi-use version).
       
    • RustyRatRod

      RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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      Did it free your hot air valve up?
       
    • Silum

      Silum Active Member

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      Well...No :D (actually I haven't checked but I'm guessing not lol). The mechanism was rotating on the shaft.
       
    • Johnny Dart

      Johnny Dart Well-Known Member

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      Heat Riser Rusty. Heat Riser. :)
       
    • RustyRatRod

      RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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      Yeah yeah. lol
       
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      • pishta

        pishta I know I'm right....

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        I got you covered...
         
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        • Silum

          Silum Active Member

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          SUCCESS!!!! pishta offered up some parts including a carb and timing cover with tab...

          I couldn't help but think it was my economizer problem with this mangled body... which happens to be a check valve that's one of the more important parts of the fuel circuit on these 1920s...
          4zcERgj8nR9UgTYIyASoFa4oL4jLB26Ib7fvO0MSVz0PZ60gZAbYZM7IcisRsU7WdCXDdHA=w1263-h947-no?authuser=0.jpg


          Well, I took the one which was in much better shape out of pishta's carb, cleaned it, and wouldn't you know it... she runs when warm!!! Starts first time cold or warm too.

          My timing is still a confusion that I will put down to my timing light for now. The heat riser I have PB'd to death and it may have some movement but I can't really tell. It could also be helping.

          Thank you again to pishta! Time to drive!
           
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          • Slowswinger

            Slowswinger Well-Known Member

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            That Pishta is a stand up guy! Time to go enjoy the car now. Glad you got it figured out.
             
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            • pishta

              pishta I know I'm right....

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              50/50 of old ATF and kerosene is a really good penetrant for frozen parts, thin enough to really get in there.I found if you spray it daily and tap the valve shaft lightly in either direction a few times and force rotate it a little more each day, it will eventually free right up. I freed a frozen block like that over the course of about a month. Even saved the bores from an overbore.
               
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              • Perseus

                Perseus '65 Dart slantsix

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              • Perseus

                Perseus '65 Dart slantsix

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              • rich006

                rich006 Learning as I go

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                I'm late to the party, but I had a pressure washer that would only run if partly choked, and a new carburetor was the fix. It had sat for the winter with 10% ethanol gas in it. I assume it was a clogged jet, which I guess you can't really clean out.
                 
              • Ian McCrimmon

                Ian McCrimmon Well-Known Member

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                Do this simple test to see if the harmonic balancer is slipping:
                Extend the timing mark to the front pulley like this (marked in yellow)...

                FBD6F1A7-2979-4262-9960-915488543C18.jpeg

                Now run the motor for a few seconds. If the outer ring on the balancer is slipping the lines will no longer line up as the outer pulley is bolted to the inner section of the balancer and the timing mark on the balancer is on the outer ring.
                 
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