GM Research Labs had been working on a sleeveless aluminum block since the late '50s. The incentive was cost. Engineering out the four-cylinder's block liners would save $8 per unit — a substantial amount of money at the time. Reynolds Metal Co. developed a hypereutectic aluminum alloy called A-390, composed of 77 percent aluminum, 17 percent silicon, 4 percent copper, 1 percent iron, and traces of phosphorus, zinc, manganese, and titanium. The A-390 alloy was suitable for faster production diecasting which made the Vega block less expensive to manufacture than other aluminum engines. Sealed Power Corp. developed special chrome-plated piston rings for the engine that were blunted to prevent scuffing. Basic work had been done under Eudell Jackobson of GM engineering, but final production engineering work was finished by Chevrolet. The Vega engine block was cast in Massena, New York, at the same factory that had produced the Chevrolet Turbo-Air 6 engine for the Corvair. Molten aluminum was transported from Reynolds and Alcoa reduction plants to the foundry, inside thermos tank trucks. The block was cast using the Accurad process. The casting process provided a uniform distribution of fine primary silicon particles approximately 0.001 inches (25 μm) in size. Pure silicon provides a hard scuff and wear resistant surface, having a rating of 7 on the mohs scale of hardness, the same as quartz, as compared to diamond which is 10. The blocks were aged 8 hours at 450 °F (232 °C) to achieve dimensional stability. The technical breakthroughs of the block lay in the precision die-casting method used to produce it, and in the silicon alloying which provided a compatible bore surface without liners. Before being shipped to Tonawanda, the blocks were impregnated with sodium silicate, where they were machined through the outer skin.[2] From Massena, the cast engine blocks were shipped as raw castings to Chevy's engine plant in Tonawanda, New York. Here they underwent the messy etch and machining operations. The cylinder bores were rough and finish-honed conventionally to a 7-microinch (180 nm) finish then etched by a new (then) electro-chemical process. The etching removed approximately 0.00015-inch (3.8 μm) of aluminum leaving the pure silicon particles prominent to form the bore surface.

D wrote:
Great links! yep single cammed iron heads that belonged on iron blocks
definitely not high tech all alloy blocks with no experience or durability
testing over time to expose its issues.

However Nissan or Datsun were amongst the best in the US but no more
My Jap father in law would not go near a new Nissan with a 10 foot chop stick
and neither would many Muricans these days.

That's what happens when the French get involved Renault ruined Nissan
The truth from SK
https://www.youtube.com/watch?v=8h_r_OuJU-w