What Car Was Equipped With a GM 3999290?
by Richard Rowe
Chevrolet has produced dozens of variations on its engines to suit different applications, each with subtle differences from others in its family. Casting number 3999290 is a two- or four-bolt main block engine designed specifically for use in trucks. Later applications would see this engine used in some of the most storied models in Chevrolet history.
Engine Basics
This engine block was one of nine different blocks used to produce the "396 Big Block" engine. Although this engine was originally slated for use only in light-duty trucks, it would outlast most other casting numbers by about two years. The 39999290 block went into production in 1968, growing to 400 and ultimately to 402 cubic inches before being phased out in favor of the "454" in 1972.
Chevrolet C/K Trucks
The engine was originally intended for application in these series of trucks. But for 1970 and later production years, the "396" was Chevrolet's top truck engine, delivering a whopping 310 horsepower. Both the rear-wheel-drive "C" series and four-wheel-drive "K" series used variants of this engine, backed by a Turbo 400 three-speed automatic or Muncie SM465 four-speed manual transmission. This block got a 0.030-inch larger bore in 1970, increasing its displacement to 402 cubic inches. Chevrolet, however, continued to refer to it as a "396" for marketing purposes.
1972 Passenger Cars
The 1972 Chevrolet Chevelle, Nova and Camaro got a 402-cubic-inch variant of this engine that produced 210 SAE net horsepower. While that may seem like a massive drop in horsepower, bear in mind that the SAE net horsepower measurement takes into account the vehicle's exhaust system, alternator, water pump and any other accessories. By previous gross horsepower standards, this engine probably produced between 280 and 300 horsepower.
Contemporaries
Chevrolet produced "396," "400" and "402" engines using casting numbers 3968854 and 3955272 from 1968 to 1969. Casting numbers 3916323 and 3935440 denote a 1968 passenger car equipped with the 396 engine, which was installed only in Chevelles, Camaros and Novas. Number 3902466 saw use in 1966 through 1969 Chevelles and other passenger cars, in 1967 through 1969 Camaros and in the 1968 Nova. Number 3902406 denotes a 1967-only block used in Chevelles, Camaros and other passenger cars. Blocks with casting number 3855962 went into 1965 Corvettes and Chevelles, as well as in some 1965 and 1966 passenger cars. Number 3855961 saw use in some 396-equipped passenger cars from 1965 to 1967, as well as in 1966-only Chevelles and Corvettes. General Motors expanded this particular block to 427 cubic inches for use in the 1967 Corvette.
References
- "Ultimate American V-8 Engine Data Book, 1949-74, Second Edition"; Peter Sessler; 1999
- Joes Antique Cars: Chevrolet Engine Block and Head Casting Numbers
Writer Bio
Richard Rowe has been writing professionally since 2007, specializing in automotive topics. He has worked as a tractor-trailer driver and mechanic, a rigger at a fire engine factory and as a race-car driver and builder. Rowe studied engineering, philosophy and American literature at Central Florida Community College.
