In 1970, there were sheetmetal revisions that gave the Chevrolet Chevelle a new look. Buyers could get their 1970 Chevelle in styles ranging from a sport coupe, sport sedan, convertible, four-door sedan, and a couple of versions of station wagons.
But, only the Malibu sport coupe and Malibu were available with a choice of one of two SS options; RPO Z25 with the SS 396 (actually a 402 ci engine), and RPO Z15 with the new 454ci engine. The base-model Chevelle was simply called Chevelle in lieu of the former base-model 300 Deluxe. Canada however, retained the 300 Deluxe name.
Engine choices started with the standard 155 horsepower 250ci six-cylinder or the 200-horsepower 307ci V8. From there, a pair of 350 V8s (both with four barrel carbs), gave you either 250 or 300 horsepower. Finally, GM lifted the 400-cubic-inch ceiling on intermediate-bodied cars this year, and Chevrolet immediately utilized their largest engines. There was a trio of 402 engines available, ranging in horsepower from 330 to 350, and finally, 375 horsepower. The 330 horsepower version came with a single exhaust, and was available in any V8-optioned body except the SS-optioned Malibu or El Camino. 1970 also saw the introduction of the 454ci engine, but it was only available with the RPO Z15 SS Equipment option.
The base LS5 454ci engine featured a hydraulic cam, and was rated at 360 horsepower. The optional LS6 version gave buyers a solid-lifter camshaft, and a “rated” 450 horsepower. Although not available to the general public as an optional Chevelle engine, an LS7 454ci engine was available over the counter. Available as a package engine, (PN 3965774), This engine was intended to be used as a “racer’s engine”, so it carried a memo stating “off road service package engine, 100+ octane fuel required”.
As a side note, according to a Chevrolet sales brochure, “You can make our tough one even tougher by adding the all-new Cowl Induction hood to either the SS 396 or the SS 454.” When you stepped on the gas, the flapper in the scoop opened to deliver more cool air into the engine air intake.
There has been some discussion about the 454ci engine being available with aluminum heads. According to Chevellestuff.net, one respected source says that records at Tonawanda show no 454 with aluminum heads being assembled. On the other hand, one person reports that he has a dealer bill-of-sale and the warranty Protect-O-Plate card both showing the appropriate code.
When it came to transmissions, the engine choice had a huge impact on what the buyer could get. If a six-cylinder engine was ordered, a Powerglide, Turbo 350, or a three-speed manual was available. Stepping up to the small block 307ci and 350ci engines, allowed the choice of the Powerglide or Turbo 350 automatics, or the Saginaw three or four-speed. When one of the 396ci (402) or 454ci engines was selected, the Powerglide and Turbo 350 automatic transmissions, as well as the three-speed manual was removed from the option list. That left you a choice of a Turbo 400 as the sole automatic transmission, and the Saginaw or Muncie four-speed transmissions as your only manual choices.