As of 2016, it is possible to find Chevy cylinder head casting numbers on OutInTheShop.com, Mortec.com and GearheadGeek.com. OutInTheShop.com lists small-block casting numbers, cubic inch displacement, years and valves. Mortec.com lists Chevy small-block V8 numbers, engine size, year and main caps. GearheadGeek.com lists big-block and small-block numbers, CID, year, intake, exhaust and CC. The websites include notes, and it offers links to Chevy big-block and 348 to 409 V8 casting numbers.
Gen I cylinder heads have the casting numbers cast in the heads where the valve springs and rocker arms work.
General Motors designed the small-block engine to streamline production and use iron more economically. The 1962 Chevy Corvette 327 was the first small-block engine with a 4-inch bore. People referred to the heads with Nos. 3782461 and 3782461X as Fuelie heads. The iconic double-hump cylinder heads used 1.94-inch and 1.50-inch valves, and the stock engines used mechanical Rochester fuel injection.
Between the two Fuelie heads, 3782461X has the larger intake port and exhaust port, with 172 cubic centimeters and 64 cubic centimeters, respectively. People who enjoy high-performance vehicles continue to favor double-hump heads. In 1997, the Gen III design included a broader power band due to wedge combustion chambers, and higher revolutions per minute due to lightweight rocker arms.