VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 Octane Booster?

Hey guys, we're having a little trouble with vapor lock. In talking with a couple of the other guys on the film shoot we're working on, they've said they've encountered the same problem. Generally the poorer quality of modern gas has taken the blame. We're wondering if we shouldn't add a can of Octane Booster to our tank when they fill us up?

Several guys have added electric fuel pumps to their delivery system, saying that when it starts to sneeze, they just flip the switch and turn that pump on, forcing the bubble through the system. I'm a little confused as to how you can have a part-time fuel pump. Wouldn't it either flood or starve the motor, depending on how you set your carb up?

Of course the vast majority of the cars on set are not Chevys, so there's a dearth of brain-power for on-site problem-solving. The most we've ever had has been 7 Bowtie cars and trucks from about 75 vintage vehicles. Usually we're the lone fliers of the Stovebolt flag!

Its not really the poor quality of the gas but rather the better quality. The gas is more volatile causing it to boil at a lower temperature. Octane has nothing to do with it and the so callled octane boosters will not help. In fact they could make the problem worse as they may contain more alchahol. You can add about a quart of kerosene to every 5 gals. of gas to decrease is volatileity. This will reduce its ooctane a little but as long as the engine does not ping under load there will be no problem. I have heard the diesel will give the same results. Adding either of these will also help to slow the evavpration from the carburetor bowl during short term storage.
An eletric fuel pump will not change the flow of gas and with the pump closer to the tank it will push the fuel past the hot area just before the present fuel pump. This is the disadvantage of the pump being in this location. The fuel entering the pump gets so hot it turns to vapor and can not be "sucked" to the pump.

When you mount your Delco 6 volt fuel pump near the tank, use a mom-on toggle switch under the dash, one that will be spring loaded and will pop back off when it is released, that way it will only pump while you hold it on. I have used one for a while on the 1928. I have never needed it on the road. Often after the car has sat for a few months (I run the system out of gas by shutting the valve below the vacuum pump and then drain the vacuum pump) I will run the electric for 10 or 15 seconds to get gas up to the vacuum pump, before I start it up the first time.