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Old 12-06-2008, 07:17 AM
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Dual AFB carbs on SBC, question

Hello Everyone.

If you have dual Carter AFB (edelbrock performer) carbs on your non-blown/non-stroked SBC I assume your running dual 500cfm carbs, since that is the lowest flow rate I can find in an AFB.

Could you tell me how your SBC runs with 1000cfm of air/fuel, what cam are you running?

1000cfm seems extremely high on a stock stroke & N.A. 350ci, even with progressive linkage. But I suppose guys are running them?

Another question: What kind of PSI does an Enderle Fuel Injection need, is it only for alcohol, and can it be streetable?

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Last edited by 04SilveradoMykk; 12-06-2008 at 07:25 AM.
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Old 12-06-2008, 10:44 AM
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its not just the its also the converter size unles u are running a 4 speed also gears size all come into play when using a tunnel ram
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Old 12-06-2008, 02:37 PM
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Quote:
Originally Posted by smrat
its not just the its also the converter size unles u are running a 4 speed also gears size all come into play when using a tunnel ram
I wasn't looking at a tunnel ram. I was looking at the Edelbrock Air Gap 4 x 2 dual plain. But there is a 3200rpm locking stall converter & 4:10 rear gears
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Old 12-06-2008, 04:09 PM
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Two four barrels on a low-rise has been my induction of choice since first seeing them on a small block Chevy as a teen at the dragstrip. I remember seeing them first on a '56 Chevy 265 with two Carter WCFB's. It was sitting there idling and the motor was going potato-potato-potato-potato. Well, I was smitten and would no longer be the same person. I was ruined for anything stock after that experience.

Setting up the motor to run two fours is no different than any other NA setup. You can choose to operate them with a progressive linkage setup (street recommended) or a direct linkage setup. You run the low speed off the rear primaries, then kick in the other 6 barrels at about 50% throttle position. This will allow some semblance of fuel economy with max power available. I have found that vacuum secondary carbs are the most street friendly. Here's the progressive linkage offered by Edelbrock and the installation instructions.....
http://store.summitracing.com/partde...5&autoview=sku
http://static.summitracing.com/globa...ad_linkage.pdf

Mechanical fuel injection such as Enderle can be operated on any fuel you wish to use, but must be tailored for the fuel used. Operating pressures are in the neighborhood of 100 psi and are provided by a dedicated pump which is run off the camshaft with a special front cover or mounted off a bracket and run with a belt drive off the crankshaft. Here is possibly the best book to read if you want to know all about mechanical fuel injection. It's 70 bucks, but hey, as we all know, education is expensive.....
http://www.racecarbook.com/firs.shtml
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Old 12-06-2008, 09:52 PM
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I have that exact intake combo on my SBC 350. I am running a 700r4 with 373 gears in a 67 camaro. I run the progressive linkage on 2-500 edelbrock carbs sittiing on top of an air gap intake. Before the airgap i had the carbs on a c-23 edelbrock dual quad intake. On my car the air gap is a significant improvement over the old intake. As for now I have the stock converter (changing that this winter to a 2800 stall with a lock up). I Run a comp cams extreme Energy 268, with afr Heads. It goes really good and i think that you will be very happy with its performance. If you are piecing this combo together don't forget to calabrate the carbs for the dual quad set up. My local speed shop was able to set me up with proper primary, seconday jets as well as metering rods that worked with my set up and altitude, I live in colorado at 5000 ft above sea level. My .02
thanks
Ron
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Old 12-06-2008, 10:02 PM
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They're pretty easy to dial in by following the Edelbrock Owner's Manual if you want to do it yourself....
http://www.edelbrock.com/automotive_...ers_manual.pdf
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Old 12-07-2008, 02:00 AM
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Dual quads (back in the day) were the only way to get serious induction for hot engines. Up until about 1965, the largest 4bbl carb you could get was 390 cfm. For anything over that requirement, you needed a dual quad or three deuces.

These days, a dual quad setup is almost always for show. A single 4bbl has consistently shown better power and drivability compared to dual quads or triple deuces. Since modern 4bbl carbs are available up to 1400 cfm, there is rarely a need for dual quads unless its for showing off.

In general, over carbing an engine leads to low torque, weaker throttle response, and greater fuel consumption - but it does sometimes provide a couple extra HP.
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Old 12-07-2008, 08:51 AM
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Been there done that will probably do it again sometime. As usual Tech is right on the money but I’d like to add my 2cents.

Dual quads are probably the easiest of the multiple carb setups to tune and run. Vacuum secondary carbs (Holley’s) can by tuned much more finely than Carter style carbs which use a secondary air valve but the Carters are a very forgiving carb and will often fit the intakes available better.

As far the total CFM in the case of both a vacuum secondary Holley or AFB Carter, the secondaries open on demand (the demand being established either by a vacuum signal or the amount of vacuum under the secondary air valve. They will only open the amount the engine requires. In most applications the secondaries will never fully open providing the full available CFM the system is capable of.
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Old 12-07-2008, 09:41 AM
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Quote:
Originally Posted by 04SilveradoMykk
Hello Everyone.

If you have dual Carter AFB (edelbrock performer) carbs on your non-blown/non-stroked SBC I assume your running dual 500cfm carbs, since that is the lowest flow rate I can find in an AFB.

Could you tell me how your SBC runs with 1000cfm of air/fuel, what cam are you running?

1000cfm seems extremely high on a stock stroke & N.A. 350ci, even with progressive linkage. But I suppose guys are running them?

Another question: What kind of PSI does an Enderle Fuel Injection need, is it only for alcohol, and can it be streetable?

Edelbrock carbs are air valve secondary and flow only the amount of air required by the engine up to their maximum flow amounts.
If your engine only needs 600 total, then it only gets 600 total, automatically.

The only consideration is when you open all 4 primaries instantaneously.
Progressive linkage is preferred for driveability,
but stomping it wide open at any speed will open all 4 primaries instantly. Your squirters will make up for the sudden gulp of air.
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Old 12-07-2008, 12:44 PM
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Has anyone used two Rochester 2gc two barrels on a tunnel ram. I would think the 350 CFM versions would work very good with progressive linkage. dare to be different,
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Old 12-07-2008, 01:02 PM
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Quote:
Originally Posted by Studebaker
Has anyone used two Rochester 2gc two barrels on a tunnel ram. I would think the 350 CFM versions would work very good with progressive linkage. dare to be different,
Years ago I think there were some 2 deuce manifolds, as well as 3 and 4 and 6.

Tunnel ram 2 deuce? YA different
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