hi. I heard switching to the two barrel super six setup would help imporve gas mileage. Does anyone know anything about this and if its true.

Yes it is true, switching to a Super six will give you increased power and mileage. This is probably the best mod you can do to a stock slant.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

In case you haven't seen it yet:

http://www.slantsix.org/articles/supersix/article.htm

Since switching to a Super Six, the difference in daily driving gas mileage has not been measureable, but I haven't taken it on a trip yet.

Hi, I have recently converted to the super six set up and my gas mileage is sort of crappy! I measured it the other day and I’m only getting around 16mpg on the freeway. I don’t know for sure what I had with the one barrel but I think it was better than this.

I think I may be over compensating for the two barrel ‘bog’ by running it a little on the rich side. I read a post somewhere that suggested that the needles could be changed to ones that have a bigger step between the economy portion and the power portion.

Does anyone know where I can get other needles of different ranges and what would be a good starting point in needle step size? At the moment I thin I have 2216 size needles in there with 120 size jets.

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'67 Dart 225 Super Six

on average what how much more mpg do you guys get with the super six?

This is one of those "loaded questions".
An engine must burn a given amount of fuel to make a given amount of power, a Super Six can allow more flow & more power so it can use more fuel then a 1 bbl, all other things equal.

But as we know, all other things are seldom equal....

The advantage to a BBD (carter 2 bbl) is that it has smaller venturies and can do a better job in mixing the fuel with the incoming air stream. The BBD also has more adjustability. (at least the later ones do) There are some who think that the fuel distribution into the intake runners is better with the 2 bbl manifold but that is hard to say for sure.

Bottom line is that you mileage is more influenced by how well the carburetor is working and how you drive.

Doctor Dodge hit it on the head.

Even if the bbd is somehow more efficent,,, if the supersix gives you more power your probably going to have your foot in it more, I know this will probably be the case when I do my supersix swap.
So i'm not really planning on getting "better" gas milage after I do my swap.
Bigger carb and better manifold = more power = my foot on the floor = more fun = more gas consumption !



Just my two cents !

sweeeet. yeah, &#@% gas mileage now!
More power=more fun, thats good enough for me.
haha