[RockHillWill]

I experienced what am quite certain was vapor lock this afternoon for the first time in my Model A. I had never experienced it before in the Model A, but it was a seldom experienced situation in racing 'back in the day' during the times between practice and qualifying where we had to sit on pit row for a little time between those two events. While I never personally had an issue, to those that did, it was explained by the Union 76 folks, that the insulation provided around the fuel lines and how it affected the 'heat soak' timing relative to the latent heat of evaporation that was blended into the fuel for that portion of the country. At the time I was in racing I understood a little bit about how the latent heat of evaporation effected the speed of the flame front as it propagated in a wedge shaped combustion chamber, but I always had some timing issues when we ran a hemi motor.

I am not to brilliant in this matter, but as of today, I feel that I did experience vapor lock in that Model A. It was in the low 90's, I run engine pans and have a nice flowing radiator. The problem occurred at four different times, all after I had let the car sit for a half hour or so. After it happened the first time, expecting vapor lock, I wet a paper towel, tied it at one end and wrapped it around the fuel line and wet it with cold water. It started each time and would run up to my normal 50 MPH until I stopped or parked again. Each time I cooled it with water, it would start and run at highway speed until I stopped again. Also, I think that I may have contributed to the issue by the fact my water pump leaks profusely and when I got home I discovered that the Boyce meter was near the top of the gauge.

In doing research on this issue, I noted that there are some that are 100% sure that vapor lock does not exist. I had not thought about that before, so I am a little puzzled that some one could be 100% sure that vapor lock does not exist, but if some one has an idea about what happened to me today, I am sure willing to listen, as I did not like stopping in the heat like I did today.

For those that might be open minded enough to consider that it might be vapor lock, what might be some 'cure' or 'adjustments'?. My only thought so far is to switch to marine gas.

As a side note, I did check for a vented gas cap, but the problem was after sitting, not driving. The car responds well to changes in the spark advance lever, and while it wont go over about 53 MPH, that's all it has ever done. It starts on the first 'stomp', accelerates as it always has and idles very low at idle, so at this time I am not suspecting anything in the ignition, but I am willing to listen to new ideas.