Quote:
Originally Posted by steve s
Larry and Marc,
In case you guys missed the earlier extensive vapor lock thread, here is a link you might find of interest:
http://www.fordbarn.com/forum/showth...k+nonbelievers
While there may be some doubt whether vapor LOCK can occur in a continuous running gravity fed engine, there is no doubt that vapor FORMATION can occur. The earlier thread shows a bunch of pictures of it happening in the top of the sediment bowl with the car idling on a summer day with the hood open. Since the initial boiling point of gasoline is around 100F, some such behavior shouldn't be a surprise. Neither is it far fetched to worry that the process might get out of hand, occur further down in the fuel path (out of sight), and cause rough running or stalling under more extreme conditions. For example, I have observed one of those clear plastic fuel filters installed in the fuel line fill up with vapor and then stall the engine--repeatedly. On the other hand, the car in the pictures barely hiccuped when the vapor bubble would periodically burp on through the system.
What mystifies me is why this is such a problem for some and not for others.
Here's one of the pictures showing the vapor bubble whereof I speak.
Steve |
Steve, that's quite a thread you were involved in. I was not reading much of the new Fordbarn when you posted so this is the first I've seen of it. Looks like many of them share MY VIEW and at least one with like mind is a bonafide engineer, David Cockey. I didn't read them all.
As you probably know, not all Model A's will have the same engine and engine compartment temperatures. They will vary from one to the next and there are many variables affecting each one. So before any conclusions can be definitively reached with any particular Model A, I think an actual temperature measurement of the fuel should be performed when the suspected vapor occurs. Then contact the makers of the particular fuel and find out the temperature specs. including the vapor pressure, exact boiling point, effect of various ethanol percentages and any other pertinent information necessary to determine its transition to vapor and also exactly when they change from winter to summer gas and back again and the specs. that go with each.
Then with a little effort you will probably reach a most believable and accurate conclusion.
Larry B.