| ole_Bill | -- 07-28-2010 @ 1:52 PM |
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I see carbs advertised for multi-carb setups with some labeled "primary" and others "secondary". What's the difference? When buying carbs, it this something I need to worry about?
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| Bill4d1merc | -- 07-28-2010 @ 2:30 PM |
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I believe that secondary carbs have no idle circuit and are used on a progressive system where they would only come into play when giving full throttle Bill
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| supereal | -- 07-28-2010 @ 2:51 PM |
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Carb air capacity must be carefully matched to the engine to maintain "volumetric efficiency" so the engine can operate over a wide range of conditions. If you use a 4 barrel carb, it shouldn't exceed 300 cfm, and have mechanical secondary control. Multiple carbs look "cool", but more often than not, you will find that only one is actually being used.
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| Stroker | -- 07-28-2010 @ 3:24 PM |
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Your E-brock "Super" cannot be set up with progressive linkage, as it isolates four cylinders for each carb. I'd use the Stromberg "leakers", as you won't have to screw with power-valve's as you would with the Chandler-Groves/Holly 94 design plus the jets are easy to access; especially given the generous distance between carbs on a "Super". I think given the displacement of your "Hot Rod" motor, two properly-jetted 97's will be "Just The Ticket".
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| sturgis 39 | -- 07-28-2010 @ 10:28 PM |
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THE PRIMARY CARBS HAVE A CHOKE AND THE SECONDARY CARBS DO NOT. DIFFERENT MANUFACTURES MAY HAVE OTHER DIFFERENCE BETWEEN PRIMARY AND SECONDARY CARBS
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| Stroker | -- 07-29-2010 @ 3:08 PM |
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Ole: I don't wish to be a "strident-pest", but there is NO "Primary-Secondary" option available to you with your Edelbrock "Super", racing manifold. This manifold has totally isolated sections with no plenum to allow for anything but two identical matched carbs. The front carb feeds cylinders 1-2-4 and 6, and the rear carb feeds cylinders 3-5-7 & 8. You MUST use two complete carbs with idle circuits, and choke assemblies, and connect the throttle linkage to open both the same amount at the same time. If you were to use two carbs with progressive linkage, you would start out running on 4 cylinders, and as you opened up the throttle, you would eventually pick up the remaining four. Not a good option for even a Hot Rod. If two Stromberg 97's are not your choice, then Chandler Groves/Ford/Holley/Edelbrock 94's with the appropriate power valves will work fine. If this is too much carb for your engine, then two Stromberg V8-60 carbs will reduce the venturi size and the CFM flow rates for better low-end performance with some sacrifice at top speed. I hope this helps clarify the challenge facing you.
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| flathead4rd | -- 07-29-2010 @ 3:39 PM |
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Is the Edelbrock super dual the only intake that is designed this way? What about the Offeys. Can you run a single carb on the two or three carb manifolds?
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| supereal | -- 07-30-2010 @ 9:01 AM |
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I was referring to the four barrel carb on a plenum-style manifold in my post. At one time, there were dozens of multi carb intakes on the market. Today, only a few, such as Edlebrock. Multiple carbs for street use opens a whole new range of problems.
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| Stroker | -- 07-30-2010 @ 10:10 AM |
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Flathead: Most multi carbs for flatmotors have a plenum, including the Edelbrock 3 and 4 carb models. The 3 carb versions can be used with progressive linkage. I wouldn't recommend progressive linkage on anything but a 3 carb though, as you can have mixture distribution problems when all the carbs aren't working together. Most 2 carb manifolds, be they Offenhauser, Edmunds, Sharp, Edelbrock Eddie Meyer, etc. also have a plenum. The Edelbrock Super is an exception.
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