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Supercharged AFB Metering Rod Springs?

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  • Supercharged AFB Metering Rod Springs?

    I'm still getting quite a bit of carbon in my exhaust. I've got a R2+ cam in my engine therefore little to no vacuum at Idle. I was checking out metering rods springs for sale on Ebay, but really don't know what I should be using or what strength I have in my carburetor now. This is what is available:

    3" Hg (blue), 4" Hg (yellow), 5" Hg (orange), 7" Hg (pink) and 8" Hg (plain) springs.

    The springs in my carburetor are not color coded so I haven't got a clue where I am at or what is stock.

    What Springs should I be using? What is the lighter spring?

    Here's the web site:

    http://cgi.ebay.com/ebaymotors/Carte...QQcmdZViewItem

    Thanks, Allen


    1964 R2 GT Hawk

    1963 Daytona Convertible
    Oakville, Ontario.
    Hamilton Chapter
    See you in Cedar Rapids Summer 2009
    1964 GT Hawk
    PSMCDR 2014
    Best time: 14.473 sec. 96.57 MPH quarter mile
    PSMCDR 2013
    Best time: 14.654 sec. 94.53 MPH quarter

    Victoria, Canada

  • #2
    AFAIK, the AFB metering rods are not affecting the idle circuit. Aren't they just for cruise and power circuits?

    While it is possible to tune a carb by-guess-and-by-gosh, a few minutes on a good chassis dynomometer will get you started in the right direction and confirm when you have it right. Here in WA cities, we have to have an emissions test every two years. Consequently, we have several test facilities which can give you accurate readings on where you are now with your carb settings. Ask around and check your yellow pages.

    thnx, jack vines

    PackardV8
    PackardV8

    Comment


    • #3
      I have the same cam and have plenty of vacuum!? If your timing is too far retarded you can have low vacuum. Just seeing some black on the tailpipes is not necessarily an over rich condition but if you are blowing out black smoke that's another story.

      I would check to make sure the rods are moving in the bores. if they are not centered in the jet when the top is put back on the carb they can situate themselves outside of the jet and then bend when the top is tightened down.

      To answer your question directly the lower the number the lighter the spring. Lighter works with lower vacuum.

      quote:Originally posted by studebaker-R2-4-me

      I'm still getting quite a bit of carbon in my exhaust. I've got a R2+ cam in my engine therefore little to no vacuum at Idle. I was checking out metering rods springs for sale on Ebay, but really don't know what I should be using or what strength I have in my carburetor now. This is what is available:

      3" Hg (blue), 4" Hg (yellow), 5" Hg (orange), 7" Hg (pink) and 8" Hg (plain) springs.

      The springs in my carburetor are not color coded so I haven't got a clue where I am at or what is stock.

      What Springs should I be using? What is the lighter spring?

      Here's the web site:

      http://cgi.ebay.com/ebaymotors/Carte...QQcmdZViewItem

      Thanks, Allen


      1964 R2 GT Hawk

      1963 Daytona Convertible
      Oakville, Ontario.
      Hamilton Chapter
      See you in Cedar Rapids Summer 2009

      On its way to a 15.097 Spring 2006.

      Comment


      • #4
        Thanks Ernie and Jack.

        I know I'm running rich and I am blowing a slight amount of black smoke which make me think I need a lighter spring.

        quote:
        While it is possible to tune a carb by-guess-and-by-gosh, a few minutes on a good chassis dynomometer will get you started in the right direction and confirm when you have it right. Here in WA cities, we have to have an emissions test every two years. Consequently, we have several test facilities which can give you accurate readings on where you are now with your carb settings. Ask around and check your yellow pages.

        thnx, jack vines

        PackardV8
        I am planning on tuning the Hawk on the dynometer this Spring. There is a shop right around the corner from me that does it. The owner last fall wanted to put my Hawk on the Dyno just to see what that old school Paxton would do but I had this bad feeling about my transmission at the time. It gave out about a week later.

        I've got a Carter Strip Kit with many rods and jets but the kit lacks any springs. I just want ALL the right parts there when and if I need them.

        I've also purchased last fall, just before my tranny went sideways a new timing light with all the bells and whistles. Timing looks bang on, and the dwell is within specs. I took each point out with a piece of cardboard to test. Little to no Vacuum at Idle.

        What springs are you running in your Avanti and which ones should I buy?

        BTW I never did find that missing flapper valve. I took the intake manifold off, went around every valve with a magnet probe to find the metal clip from the Flapper to no avail.

        Allen
        1964 GT Hawk
        PSMCDR 2014
        Best time: 14.473 sec. 96.57 MPH quarter mile
        PSMCDR 2013
        Best time: 14.654 sec. 94.53 MPH quarter

        Victoria, Canada

        Comment


        • #5
          I built an Edelbrock/AFB Hybrid carb because my original AFB ran way too rich because of that idle compenator valve. The springs I use are actually one step stiffer than the factory set up on the Edelbrock.

          My feeling is that the springs aren't your problem if the puff of black smoke comes on acceleration from a dead stop because when you open the throttle blades vacuum disappears at that moment anyway. The springs would have the most effect on light, part throttle acceleration like going up a slight grade or adjusting speed at cruise.

          You get almost zero reading on a vacuum gage? I'm 10+ with the R2+ cam on my dash gage and on a handheld vaccum gage.

          The AFB is jetted fairly rich on the primaries equivalent to a 101 or 102 Edelbrock jet I think. I run the 98's in the Edelbrock. I tried 101's and would get black smoke on acceleration. I'd have to look at my rods but if I remember correctly they are the 75/47's.

          If the clip was small enough to get past the open intake and exhaust valves it might have made a clean exit.

          ErnieR


          On its way to a 15.097 Spring 2006.

          Comment


          • #6
            Allen,

            If you are getting little or no vacuum at idle I would find out why before getting into AFB metering rod springs. You could have a major vacuum leak somewhere. Or when the camshaft was installed it was put in with a couple of teeth off the mark. I tend to think that your timing is off as somebody else suggested before. Try setting timing at 28 degrees with the vacuum advance disconnected at 1600rpm. My R2 with the R2+ camshaft pulls 17 inches of vacuum at 900 rpm and I run with 28 degrees "all in" advance

            Comment


            • #7
              Allen,

              Peter gives good advice, do that then consider the following. It is easy to have vacuum leaks at the intake manifold to head.

              Here's some unorganized observations from me.
              My vacuum at idle is around 9 to 10. The amount of vacuum you get will be affected by idle speed and valve clearance. I've got my valves set at around .020. With the R2+ cam that we both have, you can set them tighter but vacuum at idle will decrease.
              I used the lightest spring available, the blue ones. The rods get pulled down into the economy/run position by vacuum. When you step on it the rods loose the vacuum and are pushed up by the spring into the accelerate/power position allowing more fuel through the jets.
              Everyone I talk to, Ted, Jim Pepper, T-Bow have all said the same thing. These engines were built to run rich. Some black smoke on acceleration is to be expected. Missing, stumbling, constant black smoke and black sooty plugs are not to be expected. I think the acid test is how does the engine sound under power, is it reving freely, does it seem happy? I wouldn't worry too much about leaving a smoke trail, better that than running the risk of detonation which is the other side of the coin.
              By the way, how many miles are on this engine? Mine didn't start to run decent until I had about 5,000 miles on it.
              Good luck,

              Tim K.
              '64 R2 GT Hawk
              Tim K.
              \'64 R2 GT Hawk

              Comment


              • #8
                Great info guys.

                quote:If you are getting little or no vacuum at idle I would find out why before getting into AFB metering rod springs.
                I've just replaced the intake manifold gaskets from metal to the thicker fiber ones when I was looking for the missing flapper valve. Who knows, I may have had an intake manifold leak there. I haven't started the car up yet since replacing the torque converter or the transmission so I will check my vacuum again when I start her up in the next couple of weeks. I'm waiting on a new flapper valve from Phil Harris.

                quote:I wouldn't worry too much about leaving a smoke trail, better that than running the risk of detonation which is the other side of the coin.
                Once I get her back up and running I'll throw the vacuum gauge back on and see where I'm at. At this point the smoke is not too excessive and it's been the status quo since we had this conversation last summer.

                Tim, I've got about 2000 miles on her since the rebuild and my transmission went sideways. I'm looking forward to getting her back out on the road.

                Allen
                1964 GT Hawk
                PSMCDR 2014
                Best time: 14.473 sec. 96.57 MPH quarter mile
                PSMCDR 2013
                Best time: 14.654 sec. 94.53 MPH quarter

                Victoria, Canada

                Comment

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