Cold starting difficulties

[teejk]

Originally Posted by ol'George

That what they taught us, back before Chevy V8's were born.
That high octane burns slower to allow the flame front to progress over the piston area in a controlled fashion, if too fast of a burn occurs and/or multiple flame fronts are produced, a knock occurs when they collide.
A lot of owner’s manuals state just what you posted, no need to purchase higher octane than you need.
As a side note, I think with today’s economy and most folks buying regular,
it is likely that premium has been in their tanks a lot longer than regular.
When you start pushing 10- 10.5 to 1 compression, premium becomes necessary, not the low compression engines we use in our cubs.

I think any air-cooled engine should run premium in the days of ethanol additives. the ethanol has a tendency to separate from the gasoline and is not a good thing. Premium fuel is usually ethanol free (check your pump before you pay the $$$).