As 53moneypit mentioned, lots of opinions. I would like to offer another, based on 40 years plus of working on carbs of one kind or another.
First, and foremost, the question becomes:
What does the individual want, and how badly does he/she want it?
The truck engine was basically designed to produce as much low end torque as could be produced economically (build costs, not maintenance costs).
Can the engine be inproved?
On an inline six, the distance from a single carburetor to each cylinder varies greatly. This variance effects engine efficiency. Thus, if one has the perfect single carb (with the perfect intake manifold); a good set of duals will measurably outperform the single unit. How much is measurably??? As much as 8~10 percent; but generally less. These is more to be gained by installing a well designed manifold and a single four barrel (I would suggest the Carter 9400 here, but others may prefer the Holley 390; this post is not about brands). A really good single carb, with a well designed manifold and some exhaust work could be good for 30~35 percent increase at the high end, with a slight loss of low end torque. A different camshaft would increase this percentage significantly more. A good pair of duals could only add 5~10 percent additional to this gain (at increased cost).
So can dual carbs add horsepower? Yes!
Can dual carbs improve fuel economy? Certainly!
Can this be done by using any old pair of carburetors that one happens to have? If so, you need to go to Detroit; as there is a need for that type of skill.
One other comment I would like to make: dual carbs, if good carbs are used; should require exactly DOUBLE the maintenance of a good single carb :big grin: That is, you have to change TWO air filters instead of one!
Other than that, a properly selected, and set up set of quality duals should require ZERO maintenance for a couple of hundred thousand miles (unless you get some bad fuel). I have personally logged a ton of miles with dual and triple carbs on lots of different engines, from 37 CID four bangers to 390 CID V-8's. Once adjusted, just leave them alone and let them work.
As to the "kool" factor; to each his/her own opinion. I personally add multiple carbs to my own vehicles for better performance and increased fuel economy, and I obtain both. Having said that; you have to drive a ton of miles to get back the cost of the set-up through better fuel economy.
Jon.
