Q: I’m considering purchasing a 1966 Chevelle SS with a 396 engine. The owner says it’s an original 350-horsepower engine, but I don’t remember Chevrolet offering a big-block engine with 350 horsepower in 1966. He says it’s numbers-matching. So, can you clear this up?
A: Sure can. The only way this ’66 Chevelle SS has a numbers-matching engine is if the owner has made a mistake in identifying the 396’s horsepower rating. In 1966, Chevy offered a 325-horsepower base engine in the SS 396, and optional 360- and 375-horsepower engines. There was no 350 that year, as the option first appeared in 1967.
The RPO identification goes like this: STD is a 325-horse engine; L34 is a 360-horse engine, and L78 is the 375-horse engine. All of the 396s came with chrome valve covers and air cleaners. The code for the 1967 350-horsepower engine is also L34, so perhaps this owner is just mistaking the horsepower rating. Both the 350 and the 360 are 10.25-1 compression ratios.
Check the engine numbers, and hopefully the Chevelle in question is truly numbers-matching.