A Puzzler of Yore

So, something happened the other day and I was reminded of a puzzler from a while ago. A puzzler of yore, as they say. It was many, many years ago that we use a puzzle that was similar to this and I was reminded of it just the other day when a customer came into the shop. He had gasoline leaking under the hood of his car. Yeah. It was an older car, some old jalopy ready for the boneyard. Like a 1963 Dart! Ha!

Kidding. I don't remember what kind of a car it was, but it was a Toyota, I believe. And the fuel line that ran from the pump to the carburetor was leaking and gasoline was in fact leaking onto the hot exhaust manifold. He was extremely agitated. And he said, "You've got to fix this immediately because my car is going to catch fire because it's leaking gas onto this hot manifold!"

So I opened the hood. And of course, the smell of gas was everywhere. When I opened the hood, I found the leak and I fixed it.

He said, "Thanks very much. How many hundreds do I owe you? And also, by the way, why didn't it catch fire? I was worried about it was going to catch fire. But it didn't. Why?"
And I said, "Well if it caught fire, we wouldn't have made any money because we don't do fireworks!"

So this is the puzzler.
Now, I will give you some little hints here. The ignition point of gasoline, the point at which gasoline catches fire is about 700 degrees Fahrenheit. The temperature of the hot manifold onto which the gasoline was dripping? It's probably also 700 degrees. Maybe even a little bit more.

So, why didn't the gasoline catch fire?

Answer the Puzzler »

Remember last week's puzzler?

The Crusty Phenomenon

A few weeks ago we had a puzzler about spark plugs and the large air gap between the end of the plug wire and the spark plug. My mechanic, Crusty, had a flooded engine, and he pulled the plugs almost all the way out, creating an unstable connection, and it started right up. Remember this?

The question was about, "How come this works?"
And the Carl Sagan worthy answer was something about how the highest voltage appears across the highest resistance. This is true.

Now, here is this week's question.

After I explained it to our friend Stanley, he said, "Well, if that's the case, why wouldn't you want the hottest spark all the time? Why wouldn't you leave the wires dangling like this all the time? How about if you just made the spark plug gap bigger?"

He had an old jalopy, like a '63 Dodge Dart, whose spark plug gap was supposed to be 32,000-35,000th of an inch. If you were supposed to have it at 35,000, what if you increased it to like 90,000?
Then, it would really be the highest voltage appearing across the highest resistance, right?

Then you could take advantage of what we are now calling the Crusty Phenomenon!

Then you would have a really strong, heavy spark all the time.

Your car would start all the time, rain or shine, flooding, non-flooding... And you get obviously improved combustion because you'd have this more intense spark.

This is a good question. The Crusty Phenomenon could, in fact, be extended to the Stanley version of the Crusty Phenomenon...

So the question is, why don't we do that?

To be clear, we currently have bigger spark plug gaps on some modern cars, but why couldn't you increase the spark plug gap on this 1963 Dodge Dart?