HOME and how to join Forum Open Area General Scott topics Fuel injection on a Scott? Madness? Re: The Wal Phillips fuel injector

#6573
Roger Moss
Participant

Hi Erik You will perhaps not be surprised that I could not resist trying this device and had two on a 350cc Douglas Dragonfly.
They used the term “Fuel Injector” wrongly. It is a simple device to admit fuel in a ratio to air that can be varied by adjusting the length of the linkages. Wal Phillips was a successful and popular rider of “Speedway”, that being a cinder covered dirt oval. This type of racing used to be very popular here and many towns had a track that usually could be used for greyhound dog racing also. Wal Phillips tried this idea and used it successfully and so made and marketed it. I found that it worked perfectly well, but you needed a little patience to find the best settings for your bike. From memory, it may have been a little less efficient at its tickover carburation. I think that most who bought them, either did not appreciate how to set them, or lacked the patience. It was not a quick route to extra horsepower, but it was an interesting and simple device that worked well and could give extra performance if mastered and set up correctly. If you look at how an Amal type carb works, you will see that it operates in a series of steps that can be OK if left how originally set. If you just increase the main jet size, you will often find that the fuel flow from the needle jet system, will not allow enough fuel to pass at high slide lifts, to supply the increased main jet with the amount of fuel it is capable of flowing. The Wal Phillips device uses only one fuel metering device and therefore can deliver fuel in a step less range in proportion to the air.
It is a delightfully simple way of solving a problem that many designers have attempted to conquer with breathtaking complexity and cost.
I take my hat off to Wal Phillips for embracing simplicity.
Kindest Regards
Roger