Vintage Car Life Road Test: 1970 Pontiac GTO 455 And 400 Ram Air – There IS A Substitute For Cubic Inches

 

For 1970, GM senior management finally rescinded the corporate policy that limited intermediate-size cars to engines no bigger than 400 cubic inches. Buick, Oldsmobile, and Pontiac wasted no time in offering their big 455 cu. in. engines in their hot midsize Supercars. However, when Car Life compared a 1970 Pontiac GTO with the new Ram Air 455 to one powered by the existing 400 Ram Air engine in April 1970, they found that the car with the biggest engine wasn’t the fastest.

“There’s no substitute for cubic inches” is a statement many auto enthusiasts would consider an axiom, but it put Pontiac in a somewhat awkward position for 1970. “When Oldsmobile and Buick dropped their hot 400s and announced performance 455s,” noted Car Life at the beginning of this review, “Pontiac announced a medium hot 455, and did all its performance talking about the Ram Air and Ram Air IV—both 400s.”

 

The new 455 was bigger, but the 400 Ram Air engines were still hotter. As Car Life explained:

When you order a Ram Air, Pontiac makes the camshaft timing wilder, the exhaust manifolds more streamlined, and bolts the main bearings in place with four bolts instead of two. Oil pressure goes up, from 40 to 60 psi.

Why is all this done to the 400? Frankly, said the Pontiac engineers, because all these demon tweaks work better on the 400 than they do on the 445. Power comes from revolutions, er, engine revs, that is, and the 400 will wind higher than big brother.

A clarification is in order here: While you could order the Ram Air cars’ vacuum-controlled hood air inlet with the 455 engine (RPO T42, $84.26) — the Car Life 455 test car had that option — Pontiac didn’t consider it a Ram Air engine, but rather a 455 with Ram Air inlet.

 

The differences in specifications between the L75 455 and the “standard” L74 400 Ram Air engine (unofficially known as Ram Air III) were not as pronounced as CL implied. L75 engines also had Moraine 400-A main bearing inserts, four-bolt main bearing caps, higher oil pressure, and dual exhausts. With manual transmission, they also had the same cam as the 400 Ram Air III, giving 288/302 degrees duration and 63 degrees of overlap. (Automatic 455 cars, like the CL tester, used the milder cam from the standard 400-4V engine, with 273/289 degrees duration and 54 degrees of overlap.)

 

The real hot one in 1970 was still the 400 cu. in. L67 Ram Air IV engine, which had “spherized wedge” combustion chambers, bigger intake and much bigger exhaust ports, forged aluminum pistons, straight-runner exhaust manifolds, and an even-hotter camshaft giving 308/320 degrees duration and 87 degrees of overlap as well as greater valve lift. Hilariously, Pontiac claimed these breathing improvements were worth only 4 additional gross horsepower (370 hp) over the Ram Air III and 10 hp over the 455, although it was clearly more powerful than either.

 

It’s true that the 0.46-inch-longer stroke did handicap the Pontiac 455 when it came to rev potential. However, Car and Driver (January 1970) had elicited a somewhat different explanation for Pontiac’s failure to offer a truly hot 455 engine for 1970:

If you ask Pontiac engineers to explain this unseeming arrangement they kind of look at the floor, shift their weight from one foot to the other, and mumble something about not being quite prepared when the General Motors hierarchy lifted the longstanding ban on engines larger than 400 cubic inches in intermediate-size cars. They were working on a big engine at the time, a 455 for the Bonnevilles and such, but it wasn’t intended to be a high performance engine. … Still, there wasn’t any choice. If Oldsmobile, Buick and Chevrolet were going to have engines over 450 cubes in their A-body cars, then the GTO had to have one too. So in went the 455.

Still, there was also some truth to what Pontiac told Car Life:

There are at least two Supercar markets, the factory men said. One group wants a fast car with minimum fuss. The other group wants a faster car and will tolerate, indeed may even welcome, a raucous, demanding engine.

So it followed, then, that the 1970 GTO test would be a two-car test, not so much a comparison of one car against the other, but to determine what each group gets from Pontiac.

Neither of the CL test cars in this comparison had the ultra-hot Ram Air IV engine. Instead, the editors tried a four-speed Ram Air III car with 3.90 axle and an air-conditioned 455 with the hood air inlet, Turbo Hydra-Matic, and a 3.55 axle.

 

Car Life said that otherwise, “the cars were kept as similar to each other as possible, so the comparison would be valid.” Both cars had variable-ratio power steering, power front disc/rear drum brakes, and the Rally Gauge Cluster, although the 455 had a hood-mounted tachometer.

 

Both cars also had G70-14 tires on 14×6 Rally II wheels.

Car Life quickly determined:

The factory was right. In acceleration, the 400 was the winner. It got to the end of the dragstrip first, and it was going faster when both arrived, so the Ram Air 400 does have more power than the 455.

While that was true, a point that bears emphasis in the performance comparison is that the 455 car was also 225 hp heavier than the 400 Ram Air car, with the air conditioning responsible for about half that. (You could also order air conditioning with the Ram Air III, although not with a 3.90 or 4.33 axle; air wasn’t available with the Ram Air IV.)

 

However, the Car Life editors noted:

There’s more to it than that. The 400 wasn’t much quicker, with a 14.6 ET to the 14.76 for the 455. and getting there took all morning to perfect the technique.

The 455 was easy. The low-end torque is just a bit more than the tires will take, so you give it three-quarters power for the first 10 feet, then turn it all on. The transmission has been programmed for the engine, and all you do is keep your foot down. Nothing to it.

The 400 was a challenge. That is a lot of camshaft in there, and a lot of carburetor. There is no power at low speeds, and a surplus when the engine comes on the cam. Start with revs down and the 400 falls dead, just sits there choking and gasping while the seconds (and the 455) go ticking past.

Use more power, to keep the revs up in the power range, and the tires spin. Do it wrong and the car moves 10 feet by the time second gear is due.

The way it works is to catch that elusive point where the power and traction just match. With the 400, it came with a start at a steady 3000 rpm. The tires spin enough to keep the revs up, while the engine is going fast enough to keep from bogging when the tires bite. So the Ram Air owner is not only going to get more speed, he’s going to be able to take some pride in getting that speed out of the car.

Car Life editors were not fans of high numerical axle ratios, which produced better acceleration, but also more noise and aggravation. This was the case with their Ram Air test car, although I suspect the taller 3.55 or 3.23 axle ratios would have made the peaky engine even harder to launch.

 

(Incidentally, the text’s complaint about mechanical lifter clatter was either an editorial misassumption or a sign of an engine problem; the Ram Air engine had hydraulic lifters.)

 

You might assume there would be a price to pay at the pump for the bigger engine’s easy torque, but CL was surprised to find it wasn’t so:

The expectation was that the bigger engine and higher gears would just about equal the smaller engine and lower gear. It didn’t. The 455 went 12 mpg, and the 400 did an incredible 8 mpg. The smaller engine was thirstier than its size and performance would warrant.

It was thirsty because of the lack of low-speed power. Cruising along the highway, the two engine/gear combination [sic] would come out equal. But in traffic, the 455 thumps easily along. The Ram Air 400 won’t. It must be kept on the cam, so when the 455 is idling through traffic in high gear, the 400 is snarling along in second and at 3000 rpm.

Obviously, no one buying a Supercar in 1970 was very concerned about fuel economy, but with such thirst, range might become a serious concern.

 

Car Life was based in California, where the new fuel system evaporative emissions standards reduced fuel tank capacity to 19 gallons. At 8 mpg, that was only 152 miles, and you’d be glancing nervously at the fuel gauge past about 120 miles.

The first photo caption reads, “PONTIAC’S BLOCKBUSTER 400 with Ram Air was contrary to the old rule of ‘There’s no substitute for cubic inches.’ The 400 had 366 horses to the 455’s 360 bhp.”

 

The second caption reads, “GTO INSTRUMENT panel was simple, functional. Dash tach, though, had redline below engine’s potential. Shifter had Hurst parts, and was smoother than most.”

 

GTO handling was improved for 1970, mostly because Pontiac had finally conceded the advantages of adding a rear anti-roll bar.

 

This wasn’t a new idea (the Oldsmobile 4-4-2 had had a rear anti-roll bar since 1964), but it helped:

The result is very little roll, flat cornering and the ability to induce oversteer at higher speeds.

You could charge into a corner on the road course, taking a wide line, aim in toward the center, stab the brake to throw weight on the front and unweight the rear, then stomp on the gas to bring the tail end out. Both cars had enough of a good power-to-weight ratio to keep the back end out just with the throttle. The result was that, with the GTO, you could get around a race course a lot quicker than in a standard LeMans.

The high speed stability of the GTO was another area where both cars were impressive. There’s one chicane at our test track that calls for a quick flick of the wheel to the left and then a correction to the right at speed. We took it faster in the GTO, with more of a feeling of control, than in any car we’ve tested this year. Makes freeway lane changes go easier, too.

They were less happy with the ride, which for once was stable over rough pavement, but rather jiggly on the freeway. The disc/drum brakes also rated only fair, offering decent control but unimpressive stopping distances from 80 mph.

 

Another complaint was the Hurst four-speed shifter. Changes through the forward gears were fine, but it tended to hang in reverse. “We hope that Detroit thinks of another way to work the anti-theft lock with stick shifts because we’ve had trouble with the reverse lock-out on every stick shift car we’ve tested lately,” the editors groused.

The first photo caption reads, “GTO COCKPIT has buckets, console. Custom Sport wheel has simulated wood rim, is option like tilt lever. Roomy interior has more room than Grand Prix.”

 

The second caption reads, “ROOMY TRUNK would be roomier if tire was moved out of main cargo area. High lip makes packing a challenge. Wheel covering is optional.”

 

Car Life still liked the GTO’s exterior styling and the Endura nose, and were cautiously positive about the available hood pins.

 

They remarked:

The optional hood hold-down pins on our 455 GTO were handy, mainly because the hoods on both our test cars fitted so poorly you were glad to have the pins holding things together. We wish they would include lanyards to secure the pins as we are the kind that would be a hundred miles away from the gas station before we remembered the pins are still atop the gas pump.

Having the acceleration times for the two cars separated across multiple pages doesn’t make it easier to compare them, so let’s set the results for both cars in a single table:

1970 Pontiac GTO Ram Air IV 4-Speed vs. 455 Ram Air Automatic, Performance

Acceleration	400/4-Speed	455/Automatic
0–30 mph	2.5 sec.	2.9 sec.
0–40 mph	3.4 sec.	4.0 sec.
0–50 mph	4.5 sec.	5.3 sec.
0–60 mph	6.0 sec.	6.6 sec.
0–70 mph	7.5 sec.	8.2 sec.
0–80 mph	9.4 sec.	10.2 sec.
0–90 mph	11.6 sec.	12.7 sec.
0–100 mph	14.75 sec.	16.2 sec.
Standing start ¼ mile	14.60 sec. at 99.55 mph	14.76 sec. at 95.94 mph
Passing, 30–70 mph	5.0 sec.	5.3 sec.

 

As I noted earlier, the 455 car was heavier, which probably accounted for part of the performance difference, as did the lower numerical axle ratio. Nevertheless, for the 400 car to be almost 1.5 seconds quicker to 100 mph, it had to be making significantly more power on the high end.

 

Still, I can’t help feeling Pontiac was treading water in outright performance. The 1967 GTO Ram Air Car Life had tested two and a half years earlier had returned a best quarter-mile time of 14.5 seconds at a terminal speed of 102.0 mph.

The photo captions read, “FRONT DISC brakes, a GTO option, helped bring down speed in a hurry. The rear drums were finned to promote better cooling. ON TOUGH handling course, GTOs took corners like Nascar [sic] Stockers. Little roll, mild understeer were characteristic. Power on tap permitted powering out of turns.”

 

Car Life seemed less than enthralled with the interior, which now featured engine-turned metal trim (sometimes in addition to the optional woodgrain), and the editors were fairly confounded by the heat/ventilation controls. “You never really knew where the settings were for heat or cold but you just slid all three levers all the way over and hoped,” they complained. “We wish GM would, if they’re going to standardize throughout the divisions, start with heater controls.” They did like the new heated rear window.

 

They found the hood-mounted tachometer on the 455 car easier to see than the dashboard-mounted one, but they wondered about its longevity. “Think about it—every time some pump jockey slams your hood, he must bruise the tach’s innards something awful,” they mused. “From that standpoint, the location makes as much sense as mounting your boat’s expensive marine compass on the anchor.”

 

A further complaint Car Life had noted on their 1969 test car was that the Rally Gauge Cluster oil pressure and water temperature gauges were confusingly mounted upside down: The oil pressure needle would fall as the pressure rose, and the temperature gauge would dip when the engine was running hot. This was still true, and still senseless, for 1970.

The first photo caption reads, “IF YOU order the hood tach, Pontiac can fill the inside spot with a rally clock. Instrument trim includes engine turned metal.”

 

The second photo caption reads, “MASSIVE 455-cid V-8 had more torque than the 400-cid V-8, almost kept up with it on the strip. Sponge gasket is part of Ram Air system.”

 

Car Life‘s conclusion was noncommittal:

Overall, Pontiac did a good thing by branching out into two performance car markets. The 455 goes fast, and it’s quiet and civilized enough to be driven daily, under any conditions. The Ram Air 400 goes faster. It’s temperamental, it isn’t at home during rush hour, and it takes some skill to drive it the way it’s supposed to be driven. That may be a drawback, or it may be an advantage. Both cars did what they were supposed to do, and you can’t ask for more than that.

Just based on these results, I’d say the 455 made the Ram Air III kind of superfluous: The Car Life test car was a little faster, but a lighter 455 GTO with manual transmission and no A/C would have closed most of the gap and still been easier to drive and live with.

 

However, buyers apparently didn’t agree — the Ram Air III outsold the 455 4,644 to 4,146 for 1970, and the hotter Ram Air IV accounted for a further 804 units, out of a total of 40,149 GTOs. The Supercar market was fast fading by 1970, but buyers who could still afford both the price of entry (both of the test cars stickered for more than $5,000) and the price of insurance still wanted the hottest thing going — and in that regard, bigger wasn’t better.

Related Reading

Vintage Car Life Review: 1969 Pontiac GTO Ram Air IV – Here Come “The Judge” (by me)
Vintage Car Life Road Test: 1968 Pontiac GTO Ram Air – “It’s The Wildest” (by me)
Vintage Car Life Review: 1967 Pontiac GTO Ram Air – “King Of The Supercars” (by me)
Curbside Classic: 1969 Pontiac GTO Convertible – Hi-ho Silver! (by J P Cavanaugh)
Curbside Classic: 1969 Pontiac GTO The Judge: Here Come Da Judge! (by J P Cavanaugh)