At one time, Holley Carburetors (Colt Industries) were involved in LPG carburetion and modified their gasoline carburetors to supply gaseous fuel. Very little is commonly known about Holley's propane carburetors and, to best of my knowledge, the only reference to them was made in Larry Carley's book.
Gerry Flood, currently of Firexonline was kind enough to provide us with photos of Holley propane carburetors from time he was in the propane conversion business in the early 1980's. His company, Rodagas Energy Systems, also had shops in Toronto and Detroit and converted 350+ vehicles to CNG and 100+ to LPG. They become involved with Holley because Holley was also in the Detroit area at that time. They never made any money on LPG as every conversion was a 'test' or 'trial'. The profit was in selling the fuel. They also converted 10-15 various vehicles to low pressure CNG and even converted a golf cart to CNG for the CEO of the local gas company. He believes that fuel cells and hydrogen are the future, but if one could clean out the impurities from natural gas and store it in carbon, then Natural Gas would be hard to beat.
One of his projects included the conversion of the entire Windsor, ON police department with Holley in the early 80's when they had Plymouth 318cid cruisers. He reports that the conversions worked fine except in the winter when they would chase speeders before their engines warmed up. Then they got a liquid lockup on the vaporizer. He advised them to carry a coke bottle full of water to pour on the vaporizer. Of course, by then, the speeder got away!
Mr Flood got out of the conversion business because he felt that propane was/is a fuel which could not become a major alternative as there is just not enough. They saw natural gas as the real alternative and worked with a consortium of 8 gas companies, including the gas companies in Toronto and Windsor, to develop low pressure CNG. By using a carbon adsorbent in a LPG tank and a refrigerator compressor, their idea was to fill up at home overnight without the high cost and complexity of 3,700psi compressed natural gas. It almost worked. They even used ceramics from the Royal Military College in Kingston. Natural gas is inherently dirty, which doesn't matter when it's burning in your furnace. It matters a lot when filling and emptying a clean carbon filter. It quickly clogs up!
His present mission to change the world is to market a vehicle fire suppression system principally for the Ford Crown Vic, which Ford has developed but can't/won't deliver. His company, Firexonline, is working with Nobel and they are about to introduce a fire suppression system based on their gas generator technology. The system delivers AFFF foam under the car when (or if) the gas tank ruptures and ignites.
He says that he was one of the early pioneers in alternative fuels and the biggest mistake he made was investing his own money! With gasoline prices skyrocketing today, he might want to reconsider getting back into the alternative fuel conversion business.
Holley 1-BBL Propane Carburetor
Holley 2-BBL Propane Carburetor
Holley 4-BBL Propane Carburetor
Holley Propane Regulator/Converter