> You should check with your owners manual if you can. My 1986, 87 and 88
> Jeeps pointedly state in the owners manual 'not' to use any mix of
> alcohol no matter how many 'drying agents' they state they add.

Ah-yup.

As I recall, the late 70s saw the advent of "gasohol" in response to
the energy crisis (plus ca change...) and the stuff acquired a spotty
reputation, not only for being improperly handled en route to the
customer and thus absorbing water, but also for compatibility with
rubber compounds in the car that came in contact with it.

Even after these problems were licked, there were some cars that simply
didn't run well on the stuff -- many cars of the day had a fairly
narrow range of tune parameters anyway. That era when smog control
requirements outpaced engine controls wasn't always pretty!

If a '78 with a 231 is much like an '80 with a 3.8, the most comparable
vehicle of my close acquaintance, the details are mercifully blotted
from my subconscious but the general theme was that the car needed a
lot of fussing-with to get into that window between rampant knock and
bogging down and stumbling, and even then didn't care for "regular
unleaded" (87 octane at my elevation), far preferring 89 octane.

Maybe that particular car was just kind of a stinker, or something
drastic changed in those two years; but all in all, I'd suggest staying
away from the stuff in that car except maybe occasionally if nothing
alcohol-free were available.