1960 Corvette F.I. Aluminum Heads
Because all Corvette engine production and the various RPO combinations of roadracing equipment have been documented for decades, little of it is included in this story. Note that in 1960, engineers cast aluminum heads for the 315hp fuel-injected engine. Extensive testing was done by many engineers, contracted engine shops, and race teams. At the very last moment, the heads were removed from the option list due to coolant leaks. Over the subsequent years we have seen a number of sets of NOS, never-used, factory aluminum heads.
In talking with Chevrolet engineers of the day, the new aluminum foundry pouring process made the heads too hard. As a result, the steel head gasket could not adequately seal. Cylinder compression then caused engine coolant to be purged-mostly into the cylinder, then out the exhaust valve. Factory aluminum heads were not seen again until 1967, this time for ultra-performance big-block engines. It would be interesting to see if one of today's head gaskets with a panograph (O-ring) would seal the '60 aluminum heads.
The RPO 590 348 was now rated at 340 horsepower (up from 320) and cost $236.75. The hottest Tri-power 348 was still RPO 593 with 350 horsepower, but now cost only $258.30 extra.
1961 is best known for some pretty sharp and very quick sheetmetal, plus the first year of the legendary 409 engine. Producing an advertised 360 horsepower, it was a bored and stroked 348 and had the big 348-cid/350hp heads. Its induction consisted of an aluminum high-rise intake manifold and a single Carter D-series AFB carburetor. In reality, it looked like a 340hp 348 except for its silver-painted valve covers (all 348s were orange). There were no 409 body numbers or script. The '61 409 cars had the same front and rear "flags" as the 348. Only 142 409s were sold due to limited block casting availability. We have always believed that Chevrolet Engineering rushed the 409 into service to stay ahead of the competition. By doing so, it truly set the stage for 1962.
Luckily for enthusiasts, '61 production data missed the GM fire. Total 348 engine production was 66,929. Three-speed manual transmission sales totaled 324,836. Four-speed transmission sales were 7,073. Three-speed with overdrive totaled 17,738. For comparison, how many 283-powered Chevys were sold in 1961? Exactly 613,954, 51 percent of the total. Total big car sales in 1961 were 1,193,977. What's this all mean? Well, for sure, there was a lot of cruising in 283- and 348-powered big cars in 1961. The other 48-plus percent were six-cylinder-powered.
Near the end of the '61 model year, a few select 409 racers received bigger '62-era heads, camshafts, and dual four-barrel AFB carburetor induction. We believe Chevrolet Engineering communicated this updated package with the NHRA and received its approval for legal S/S competition. We have never seen an RPO '61 Chevy with this dual four-barrel, big head, big cam package. We believe Chevrolet Engineering put it out there prior to 1962 in order to stay ahead of the competition.
Total 348 sales in 1958-61 are estimated to be almost 190,000. Solid lifter performance engine totals are about 53,000. Total F.I. 283 big cars in 1958-1959 were a drop in the bucket-probably no more than 50 cars. Corvette performance engine totals are known and have been well documented, but do not play a large part in this story. In all, we don't know anyone who does not like and appreciate Chevrolet's early eye-popping performance history. During the last 25 years, this is why '50s-60s nostalgia has been so popular and everlasting. We certainly don't live in the past, but Chevrolet's early performance history is sure fun to remember, reflect on, and, to some extent, relive at cruise-ins, regional events, and club conventions.
Next up: 1962-1965.