The Camaro Z-28 is of course another one of those cars that became legendary and perhaps the most iconic of the muscular pony cars. But it was never intended to be primarily a drag strip or red light terror; instead its initial purpose in life in 1967 was to qualify it for the new SCCA Trans Am Championship circuit, which had a 5 liter displacement limit.
That was mighty easy for Chevy to meet: just take on of its 365 hp 327 Corvette engines as sold in 1964-1965, and substitute a 283 crankshaft, to yield the requisite 302 cubic inches. That’s really all it took to create what became the ultimate gen1 small block engine, one rated at 290 gross hp, but actually making some 350 or more. And the actual T/A racers were making 450 or more. All with parts that had been around for years; decades even, in some cases.
The only problem was that its torque didn’t really kick in until some 4000 rpm, which is why it wasn’t so ideal for the street, but by shifting it at 7500 rpm, it was a veritable giant killer, as well as a bargain-basement American Ferrari.
The key to power is breathing, and the Chevy small black started out life back in 1955 with better lungs than average. And they got only better with time, as its heads sprouted ever-larger valves and ports, and those valve were actuated by ever-wilder cams, and were fed by ever larger carbs (or fuel injection). The ultimate heads were the ones with 2.20″ intakes and 1.60″ exhausts, first intended for the still-born 1961 315 hp FI 283, and then used on the 340, 350, 360, 365 and 375 hp versions of the 327. The cam was a version of the “Duntov 30-30”, in this case the same one used in the ’64-’65 365 and 375 hp 327s. And the aluminum intake and Holley 780 cfm four barrel were also used on the 365 hp 327.
Why would a smaller displacement version of that engine (365 hp 327) make almost the same amount of hp? Because the flow of the heads are the limiting factor, and a shorter stroke engine like the 302 can then just wind higher to make essentially the same power. That affects the torque and power curve, and necessitates the 7500 rpm shift points (it could be wound out to 8000 rpm, but to no better effect).
The R&T test car also had the “official” dealer-installed tuned tube headers, a recommended option to help uncork every one of its potential ponies.
R&T was known for its conservative (read: slow) acceleration test results, an issue they fixed in 1980, which then made their results comparable to the rest of the buff books. Also, they were forced to use 7000 rpm shift points because the clutch was acting up, refusing to re-engage above that engine speed. Nevertheless, they still got the Z-28 down the drag strip in a respectable 14.9 seconds @100 mph. And from 0-60 in 6.9 seconds. Other did better, but that 100 mph through the traps in the quarter tells you it was making some serious power. Top speed was a brisk 142 mph.
Interestingly, the Z-28’s suspension was not significantly different than other V8 Camaros, with the same front spring and anti-roll bar as a base Camaro. The rear springs were beefier multi-leaf units. The resulting handling was very good: “a stable, near-neutral car that has no trouble setting excellent lap times around any reasonably smooth course”.
The one bitter pill was the steering, as the optional power-assisted unit as tested lacked feel. The manual steering would have been a better choice for the hard core speed demon. The brakes also acquitted themselves quite well, except for the usual front/rear proportioning.
R&T summarizes by pointing out that the Z-28 was a bargain at the price, offering blistering acceleration, commensurate handling, seats for four, and a top speed of 142. The only downside was its “tractability”. But then the same could be said for a Ferrari GT of the time too, right down to the 7500 shift point. No wonder the Z-28 became such a legend.