12-06-2020, 03:27 AM
There was evidently a change in the source/composition of the pump gasoline in the USA around that time [less volatile]. I have some automobile engineering text books published by the American Technical Society dated 1925 which mention the new 'heavy fuels' and discuss methods to overcome their disadvantages, whilst still taking advantage of their 'higher value of power units'. Heating the entire carburettor gets a mention, as does fuel injection; 'nevertheless, there are many engineers who adhere to the view that sooner or later fuel injection will supplant present systems of carburetion, and progress made recently with aviation motors of fuel injection types may seem in some measure to justify this view ' . There's an illustration of a Holley 'temperature regulator' , which apart from the driver adjustable dashboard control, worked like a 1950s/60s heated air intake. Holley was said to 'recommend a temperature regulator for use with its own and other carburettors', so it was also available as an after-market accessory.