1970's Golden Chevy Era - Rare V-8 Performance History Part 5

1970-1972: The End Of The World As We Knew It.

Doug Marion Oct 1, 2008 0 Comment(s)
Sucp_0810_04_z Rare_v8_performance_history 70_ls6_chevelle_ss 2/11

Another beautiful, low-mileage '70 LS6 Chevelle SS was owned by Graham, North Carolina's Roger and Penny Ausley of Ausley's Chevelles fame.

The base RPO Z27 Super Sport package cost a grand total of $289.65 and 12,476 were so ordered. The base SS engine was the L48, 300hp 350. The extra cost SS big-block 350 horsepower 396 (402) totaled $152.75 and had sales of 1,864. The 375 horsepower 396 (402) cost $385.50 and had exactly 600 sales. Super Sport Camaros totaled 12,496 and Super Sport Novas were 19,558. A total of 27,136 Camaros had the Rally Sport package. The '70 Camaro Z28 featured a great-running 360 horsepower 350 engine. A total of 8,733 were sold.

By model year-end, Corvette sales tallied 4,473 LS5 454s and 1,287 LT-1 (370 horsepower 350) Corvettes. A mere 25 had an M22 heavy-duty four-speed transmission; a paltry 679 had 3.70:1 gearing; a scant 14 had 4.11:1 gearing; and only five had 4.56:1 gearing.

Just 25 Corvettes were ordered with the ZR-1 off-road racing package, which used the solid lifter LT-1 engine. Even more scarce was ZR-2, which was the same concept with the LS-6. Although advertised, none were built.

Sucp_0810_05_z Rare_v8_performance_history Cowl_induction 3/11

All '70 LS6 454 Chevelle engines had an aluminum pancake intake manifold for cowl induction hood clearance. In early- and mid-1970, we saw a few without cowl induction that had an L72-type aluminum high-rise manifold. We could never prove the intake manifold was a factory deal, but it should have been.

Debuting in 1970 was the 400ci small-block V-8. It was created as a low rpm torque engine mainly for big car use. Lore has it that Mark IV big-block engineers asked how a small-block could have more displacement than a big-block 396? To correct the dilemma, they decided to over-bore the cylinders 0.030-inch for 402 cubic inches. They were correct in doing so, but nobody told the body design group to drop the 396 fender emblems and add 402s. The '70 was continually referred to as a 396 strictly due to habit. It also had a lot of brand equity and street cred.

This-the first year of the 454 big-block-saw the base LS4 bolted into 14,280 big cars. The LS5 was also bolted into 2,459 big cars and 4,473 Corvettes. The LS3/330hp 396 (402) was for non-Super Sport Chevelles and El Caminos. There was a whole lot of big-block Chevy action going on in 1970. And don't forget crate engines and short-blocks.

In 1971, I was working at the Los Angeles Area Chamber of Commerce as an assistant manager on several department committees, including one called Clean Air. Back then, the smog was so thick, I could see it as I looked out my window at the Union 76 building some 200 feet away. Most commuters returned home each evening with a splitting headache.

LA Mayor Sam Yorty asked me to write some speeches in favor of stricter emissions. Government efforts eventually resulted in a 50 percent improvement in air quality.

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A gaggle of smooth-idle big-blocks that seldom saw 5,500 rpm but ran great were the 325 hp and 350hp 396s (402) and the LS3 early-'70s 396 (402). This engine is equipped with every conceivable emissions item and power accessory. Engine still did its job admirably.

But it came at a cost. On all 1971 (and 1972) GM cars and trucks, compression ratios dropped, then camshafts were retarded about four degrees-all to decrease tailpipe em issions levels. Sadly, torque production and engine efficiency dropped. As a nation, we were consuming more gasoline in order to reduce tailpipe emissions. The EPA oversaw emissions regulations and the Department of Transportation oversaw oil imports.

How confusing.
Nova V-8 sport coupe sales in 1971 dropped to 77,344. Camaro V-8 sales went down to 103,452. Chevelle V-8 sport coupe sales fell to 207,087. Chevelle convertible V-8 sales dipped to 5,089. Monte Carlo sales dropped to 128,600. El Camino V-8 sales slipped slightly to 40,548.

Yes, there were plenty of four-door and station wagon V-8s, but they don't count in this performance engine story series. Full-size Chevy V-8 sport coupes sold in 1971 totaled 238,793. Big car V-8 convertibles sold were 4,576.


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