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_01_z Rare_v8_performance_history 70_ls6_454_chevelle 1/11

This '70 350hp 402 big-block was ordered in a state that had no emissions rules and regulations-hence the engine had no A.I.R. (Air Injection Reactor), which pumped oxygen into the exhaust system. Yes, this did indeed restrict exhaust flow, but it also lowered NOX particulates.

Try and remember what was shakin' in the Chevy world back in 1970 to 1972, and while you're at it, you might want to recall what evolved with the various Chevy V-8 engines since 1955.

We think 80 to 90 percent of what's important today first happened back then, but it's never been fully documented. While 1970 was the beginning of a new decade, it was the last year of a great high-performance decade-and-a-half.

It was also the first year for peak RPO engine cubic-inch-displacement (454), as well as King of the Hill for maximum advertised horsepower (450) in the golden age (1955-1970) of Chevrolet performance.

For many Chevelle fans, 1970 was when the best-looking Chevy of all time was created. You know, "America's Greatest Super Car," the LS6 454 Chevelle Super Sport. We think the '70-'72 Chevelle side, roof and rear lines are unparalleled, and the 1970 front-end design is absolutely Number One.

Sucp_0810_02_z Rare_v8_performance_history 70_350_hp_402_big_block 2/11

Few have ever seen a '70 LS6 454 Chevelle without a cowl induction hood. Well, here's an original owner example. It has a rare dual-tapered snorkel air cleaner. Yes, it was very restrictive. Remedy: Turn the lid upside down to expose the entire filter assembly.

Chevy for 1970 also introduced the Monte Carlo and an all-new second-generation Camaro. You bet there were other great-looking models and front ends. Perhaps the very best is yet to come if you consider the upcoming 2010 Camaro.

Total 1970 Chevelle V-8 sales were 594,738. That's averages out to nearly 12,500 in each of the lower 48 state. Its V-8 Sport Coupe sales were exactly 316,000. Add in another 45,865 V-8 El Camino sales. Super Sport 454 totals were 13,248, of which there were 8,773 RPO 360hp LS5s and 4,475 RPO 450 hp LS6s.

Super Sport 396 (402) Chevelles included 2,144 RPO L78, 375hp versions and 53,599 RPO L34, 350hp 396s (402). Another 9,338 Chevelles had the 330hp, oval port 396 (402) RPO LS3. The L34 and L78 were made prior to the introduction of the SS 454, according to GM assembly line lore. Lastly, 18 big-block L78 396 (402) Chevelles were ordered with L89 aluminum cylinder heads. Total for V-8 Chevelle convertibles was 7,141.

Sucp_0810_03_z Rare_v8_performance_history 70_ls6_454_chevelle_ss 3/11

For many years, one of the finest totally original '70 LS6 454 Chevelle SS cars was owned by Virginia's Bill Bonham. If cars or engines could only talk.

The first year Monte Carlo ended up selling a grand total of 145,976, which included 3,823 SS 454s. The Monte was introduced as Chevrolet's top-of-the-line entry to compete with the Ford Thunderbird and the Pontiac Grand Prix. It was essentially an SS Chevelle from the firewall back, less the taillights. The front end was extended and featured singular headlights.

Novas continued to be popular in 1970. The Super Sport sales included 1,802 350 horsepower and 3,765 375 horsepower 396s (402). Would you believe the total 1970 Nova sport coupe sales were a whopping 226,283? That's 70 percent of total production. And 107,667 of them were powered by V-8s.

The new Super Sabre-looking, second-generation Camaro had V-8 sales totaling 112,323. Not bad considering its late introduction. A GM assembly plant labor issue caused the '69 Camaro to be sold through December, 1969. Records show that the '70 Camaro did not arrive until February, leaving only six months for sales.

Sucp_0810_04_z Rare_v8_performance_history 70_ls6_chevelle_ss 4/11

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 5/11

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.

1971
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.

Sucp_0810_06_z Rare_v8_performance_history 396s 6/11

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.

Sucp_0810_07_z Rare_v8_performance_history 396_big_block 7/11

A hot 396 (402) big-block that needs to go down in history as a high rpm monster is the RPO L78 with 375 hp. And 1970 was the end of its production run (Chevelle).

The 1971 RPO LS3 (300hp 402) Chevelle sales were 17,656 and LS3 Camaros numbered a scant 1,533. The RPO LS5 (365hp 454) Chevelles were 9,502, full size cars were 6,831 and Corvettes were 5,097. Really rare was the RPO LS6 454 in the Corvette. Try 188. Chevy finally built ZR-2 Vettes-an even dozen (all LS6 powered). Corvette LT-1 350 sales were low at 1,949, eight of which were ZR-1s. The L48 (270hp 350) Nova sales were 7,016. Camaros were 6,843. Chevelles were a whopping 78,771.

1972
Not many changes in 1972, but engines were now all rated in net horsepower terms instead of gross. This made them seem a lot lower than they were. Total Chevelle V-8 sport coupe sales went up 22,138 to 242,095. Chevelle convertible sales dropped 236 to 4,853. El Camino V-8 sales went up almost 14,300 to 57,147.

Sucp_0810_08_z Rare_v8_performance_history Yenko_deuce_nova 8/11

One of the best-launched new cars was the '68-'72 Chevy II / Nova. Add a potent L78, 375hp 396, axe the restrictive exhaust system, and you had a super car. This is why the COPO Novas were so popular. Ditto on the '70 LT-1 350 Yenko Deuce Nova.

Monte Carlo sales climbed 52,219 over 1971 to 180,819. Total Chevelle V-8 sales went up 117,265 to 605,289. Chevelle and El Camino L48 350 sales were 125,708 (up 46,937). Chevelle and El Camino SS 454 LS5 sales dropped to 5,333, but Chevelle SS cars jumped to 24,946 from 19,293 the year before.

The SS 454 option for the Monte Carlo was dropped after 1971, but you could still get a 402 big-block. Corvette sport coupe sales totaled 20,496, while convertibles were a mere 6,508. Total Chevelle Nomad V-8 wagon sales were 7,768. The RPO LS3 402 was ordered in only 970 Camaros and 20,031 Chevelles, El Caminos and Monte Carlos.

This was the last year the big-block Camaro was available in all states-except California-where it was not certified. Only 970 were sold, despite the bargain-basement price of $96 for the RPO. The RPO LS5 454 was in 3,913 Corvettes (also not certified in California). It was also in 5,333 Chevelles and 8,034 full-size cars. The RPO LT-1 350 was ordered in 1,741 Corvettes. The RPO L48 350 was in 5,584 Camaros.

Sucp_0810_09_z Rare_v8_performance_history Chevelle_vs_corvette 9/11

What's the difference between a 360hp 454 Chevelle and a 390hp 454 Corvette? Nothing, except the exhaust system and, of course, the horsepower rating.

The rarest Chevy go-fast RPO package in 1972 was the Corvette ZR-1. It cost a hefty $1,010.15 extra. Only 20 were so ordered. All of them were LT-1 350-powered.

And then it was over. For the next decade or so, performance from Chevy and Detroit pretty much took a nap. Even the fabled Z28 died after '74-Chevrolet's people supposedly would rather it be dead than to desecrate the name. The emphasis shifted from all-out performance to luxury as the offerings got bigger, heavier, slower and more option-laden. In the mid-'70s, two-door personal luxury cars like the Monte Carlo, Grand Prix and Cutlass exploded in popularity and, except for the Corvette, performance car sales died. It wouldn't be until around 1984 that Chevy would awaken from its slumber and start putting horsepower back into its automobiles.

Sucp_0810_10_z Rare_v8_performance_history Higher_ratio 10/11

To be efficient, Chevy V-8 engines generally need a compression ratio of 9.5:1 or higher. We've had a number of 8.5:1 compression engines-stock and modified-and they were pathetic performers. We once changed camshaft, intake, carburetor, headers and ignition in a Q-jet 454 like this one. Result: The mileage almost doubled (from 8 stock to 14-15 modified) and the Chevelle ran mid-high 14s using low and Second gear in the TH400.

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