Model A VAPOR LOCK ?

[Bob1942]

It was really hot yesterday and sunny ... I took the A out for a spin and after a few miles it began to run rough I opened the hood the engine was really hot ! ... The water in the radiator was ok ...I returned home no problem but it did not run smooth like it normally does adjusting the mixture did not help the engine sounds like it is not getting enough fuel ... I let it cool for a few minutes and started it again and it was nice and smooth no problem ... I am wondering what is the most likely reason for the rough running engine in my Model A on a really hot day ? Can a Model A have vapor lock ? or fuel boiling in the carburetor ? BOB

[Bob1942]

Originally Posted by Bob1942

It was really hot yesterday and sunny ... I took the A out for a spin and after a few miles it began to run rough I opened the hood the engine was really hot ! ... The water in the radiator was ok ...I returned home no problem but it did not run smooth like it normally does adjusting the mixture did not help the engine sounds like it is not getting enough fuel ... I let it cool for a few minutes and started it again and it was nice and smooth no problem ... I am wondering what is the most likely reason for the rough running engine in my Model A on a really hot day ? Can a Model A have vapor lock ? or fuel boiling in the carburetor ? BOB

Update to the rough running ... I remembered this occurs when I stop for a traffic light or stop sign ... I recently met a guy with a 29 four door he had slit a piece of rubber tubing and fastened it over the steel fuel line to the carburetor ... "Whats that for I said ? " he replied that on a very hot day when you stop at a stop sign the engine goes to idle and there is not enough fuel flowing in the carburetor to cool it properly then the fuel in the fuel bowl on the carburetor can boil making the engine run very rough ! the tubing was to keep the fuel cool ! in the fuel line and hopefully prevent this ...Well I now have a piece of tubing installed on my fuel line to the carburetor to see if this helps ...I used the opaque white tubing 3/8 inch diameter with the cloth woven in it that I had laying around ...I cut the tubing down the side in a spiral with a box knife (no easy task )and wrapped it around the fuel line to insulate it ...Can't hurt and it will come off real easy later ... BOB

[bobss396]

Yeah, you got vapor lock. The gasoline boils in the line or carb and will usually stall it out and not run until it cools to a point.

The insulation should work, I saw an old timer in a pinch insulate the fuel line with a bunch of wooden spring clothes pins clamped to it.

Bob