In 1922, less than three years after the end of World War I, gyro instrument pioneer Lawrence Sperry and his wife, Winifred, landed Sperry’s self-designed Messenger single-engine sport biplane within walking distance of their hotel in Detroit to attend General Billy Mitchell’s wedding. According to the Sperry biography Gyro!, by William Wyatt Devenport, fellow wedding guest Edsel Ford told him, “You ought to be able to sell this to the same type of people who bought our first cars.”
He invited Sperry to visit with him and his father, Henry Ford, for tea the next day. Edsel promised to put a sheet on the ground of the Ford estate, “showing you where to land.” Sperry described the elder Ford’s assessment of the tiny airplane. “Mr. Ford’s eye immediately went to the motor, and he began asking questions. I explained to him that the cylinders had a steel lining inside and blocks of bronze were cast in the head for the valve seats. He thought this was a very clever idea. He criticized the fact that the fins were machined, as he said he believed that sand blasting would do the trick, as well as be a better radiator.” [Readers have commented that “sand blasting” is likely a typo on page 229 of the book. “Sand casting” is more likely what Ford said or meant.]
After suggesting that all-metal construction would be better than fabric covering in a mass-production scenario (Sperry agreed that it was), Ford said he could produce the three-cylinder, air-cooled radial engines for $50 each, and that the entire aircraft should cost no more than one of his Model Ts.
“In stepping around the plane,” Sperry wrote, “I showed Mr. Ford how the machine could be made into a two-seater by taking the cover off the rear cockpit, which immediately could be used as the back of the rear seat by pushing it into place. That impressed him very favorably because of using the cover for two purposes.”
Sand blasting or sand casting? Sand casting makes a lot more sense to cast the cooling fins of a typical cylindar head. Sand blasting is to too uncontrolled to get even spacing and even thickness from fin-to-fin.
“Sand casting” certainly seems a lot more likely. However, Page 229 of the book Gyro clearly says “sand blasting,” claiming to quote Sperry, directly. But in support of your point, that introduces two possible typos. Author William Davenport could have made a mistake, or it could have been Sperry, himself. A remote third possibility, since the distinction was between “machining” and “sand blasting” is that Henry Ford believed that the fins of a sand-casted cylinder could have been sufficiently refined by crude sand blasting, rather than precision machining.