2bbl conversion -- worth it?

nm9stheham said
My family had several Darts with /6's, and out of the auto trans cars, my mom's 1980 Aspen with the 2 BBL Super Six got better gas mileage than her 1969 Dart 1 BBL. I understand that the 1980 Aspen had the lean burn system, and it certainly had a locking torque converter, and I am 99% certain that it had a lower rear axle ratio, so those are unknown factors in the equation. The Aspen was also significantly 'perkier' than the 1 BBL, even though it was a bit heavier.

Results are going to depend on a lot of factors. Just the rear axle ratio, and the resulting RPM's on the freeway will make a big difference, as that sets the cruise vacuum level and if the power valve in the carb is open while cruising. And, how you drive it and how you tune it up makes a big difference. So without knowing those factors for a given situation, like for Slantsix64's car, you can't draw broad conclusions from one setup.

That car was designed as a complete package to do what it did. It had an A999 lockup transmission with a low first gear to aid in that perkiness and the lockup converter to help drop highway RPM similar to an overdrive gear. And as you already pointed out, it had the learn burn system.......which it sounds like was operating properly.......however rare. lol

That's the difference here. He is talking about changing the package he has, not completely engineering a new one to give th purpose of economy.

That Aspen and many others like it did get good economy, but it was not because of the two barrel carburetor. It was because of an entire package that was built to provide good economy. With a one barrel on that same setup, it would have gotten even better mileage than it did, but it would have been such a slug that they would not have sold many Aspens. lol.