Your Dart probably liked the lower volatilty of the regular gas.
Modern gas is formulated to work with injection and consequently is more
volatile than gas for carburetors with float bowls.

There is a dazzling array of different gasolines available at the track on
Vintage Race weekends. The brochure reads like a winery's product pamphlet
ie "muscular yet focussed, with an intense oakiness"......... :-)

On 10/19/06, John Bange <jbange@gmail.com> wrote:
>
> >   So. Is it ok to run out the full tank with the higher octane?
>
> Without getting into too much detail, octane rating is basically how
> evenly the fuel ignites. Most engines are fine with 87. Some high
> compression engines need higher octane to prevent pre-ignition. The
> 2.1 wasserboxer could probably run on 40 octane. Higher octane gas
> than you need shouldn't make any difference. That said, I had a '67
> Dodge Dart that ALWAYS ran better (and got better mileage) on the
> lowest quality gasoline I could find. Perhaps the cheap stuff was
> adulterated with kerosene, or the expensive stuff had whatever fancy
> additives, and that old 273cid, 2bbl carb, mechanical point ignition
> detroit water pumper was partial to kerosene over fuel injector
> cleaner.  Mysteries of the universe...
>
>
> --
> John Bange
> '90 Vanagon - "Geldsauger"
>

--
Jake
1984 Vanagon GL
1986 Westy Weekender "Dixie"
www.crescentbeachguitar.com