More than 45 years have passed since this happened. The world was certainly a different place then. The cops had chased most of the hippies off Sunset Boulevard. Deep Throat was gurgling down on Santa Monica. Fuel was still cheap. Detroit muscle was at its pinnacle … but beginning to droop like candles on a birthday cake. And Chevrolet had a problem: mediocre Camaro sales and the intricacies of a totally new car prompted the “Wizards of Warren” to deviate from the normal late-summer long-lead festivities and delay the introduction of the second-gen Camaro until February 13, 1970. The press rollout consumed a full day at the (now defunct) Riverside Raceway.
Of the 112,323 units built, 8,733 were Z-cars. Car Craft got its hooks on a pre-production prototype and flaunted it weeks before the official release date. Even in car-jaded LA, the ’70 1/2 Z28 rocked: Hugger Orange, big black stripes, new all-forged, solid-lifter 360hp LT-1 engine, M21 four-speed, 4.10s, and a real snotty attitude (or maybe that was us).
A few years of Trans-Am racing had enlightened the suspension engineers. The new car had larger control arms that swept to the rear, improving the ball-joint angle and providing tastier caster and camber geometry. Instead of the standard 0.6875-inch unit, a 1.0-inch diameter bar led the way. At the rear, support came from five-leaf bundles (125-lb/in spring rate), staggered heavy-duty shocks and a link-type stabilizer bar.
To soften the ride, the springs had a lower rate than the first-gen; shock absorber damping rates were increased accordingly and a rear antisway bar became standard equipment. But we were drag hags. We didn’t care how well the new Camaro handled nor if it even had brakes. Nope. We wanted to burn rubber, bang gears, and listen to that engine ring. We needed a baseline. We called CJ (Hart) at Lions for some track time.
On the flatlands of Wilmington, we loosened the power steering belt and snatched the element from the twin-snorkel air cleaner can. It ran a best of 14.11 at 102.73. Earlier high-performance variations had been universally hobbled with the heinous Inland shifter. Evidently, someone heard the shrieks of thousands, so the second-gen Z28 had flawless Hurst linkage strapped to the close-ratio transmission.
But the Camaro had an Achilles heel that began to out long before it ever sniffed slick tires. The Monday after the Lions gig, the phone rang funny. One of the guys was by the side of the road baking in a public booth watching the Z28’s driveshaft twitching on the tarmac in the morning rays. The rear U-joint had sheared clean. Wah? We determined it a fluke. The car was so new that the dealer had to replace it with a part for a 1970 Chevelle. We forgot about it.
Chevrolet service bulletins advocated certain ancillaries for maximum performance. At the top of the list: tubular exhaust headers with equal-length primary pipes. Since there was nothing like that in the aftermarket, Hedman prototyped them on this Z28, putting up 1 3/4x30-inch primaries that merged into a 10x3-inch collector.
The remainder of the exhaust system was original equipment, including the restrictive reverse-flow muffler and exhaust pipes that were flat on the bottom and then made some roller coaster curls and twists to fit where they were supposed to be. Further, the driveshaft tornado had whipped a serious crimp into one of them.
To amend the factory-lean air/fuel ratio, now exacerbated by the freer-flowing exhaust, we replaced the #70 primary jets with #73s but left the secondaries intact. We ran the valves hot: 0.024 on the intakes, 0.030-inch on the exhausts. We peeled out to Irwindale to have a look-see.
The Z had no fresh air intake, so we removed everything but the baseplate. The first pass was a high-16 as the engine ran out of air at 4,000 rpm in each gear. There was some sympathy going on underhood. The Holley carburetor was close enough to the insulation blanket to suck it down and choke the airflow. We put the snorkel top back on but left element out.
Remember those hinky leaf springs? We made some spring clips for the front of them to hold the main and second leaves and cinched the second and third leaves accordingly. The quickest and fastest pass of the day was 13.90 at 105.53. We tried to better it, of course, but on the next pass, the U-joint made like a hand grenade. We exhaled and traipsed over to the cheesy beer-and-burger bar across the street and dialed Clippinger Chevrolet in freeway-close Covina. The flatbed cometh.
Chevrolet engineers suggested the Jenkins/Lakewood slapper bars, but alas, there were none for this too-new Chevy. Very soon, Lakewood’s Joe Schubeck sent us the first pair off production. The Grump confirmed our suspicions about snubber height and clamp tightness and said to get some 8.90x15 (Goodyear) slicks and put ’em on 7-inch rims. Then we stopped by B&W Automotive in South Gate to see Dick Burley. He converted the vacuum-controlled, aluminum single-point distributor we’d brought along to full centrifugal advance.
Back at Irwindale, we made three passes in street trim for an average of 13.81/105.88. Open headers sliced the time to 13.60 and upped trap speed to 106.90. With the Goodyears at 12 psi, 6,000-rpm launches, and changing up at 6,100, the car ran 13.38/107.64. We pulled the AC43 plugs, found them lean and upped the primaries to #74s. We plopped in Burley’s distributor with 16 crankshaft degrees of advance for a total of 50. The car averaged 13.22/107.73.
The jetting looked right but the engine needed more oats. We jacked timing to 52 degrees and gained 0.08-second overall. Goodyear’s bled to a scary 8 psi (the slicks weren’t pinned to the wheels), the Z28 ran a best of 12.93/108.76.
A few months down the road we were informed that early cars had been fitted with too-soft front bushings that precipitated the spring deflection and the ensuing driveshaft shuck. As a running change that first year of production, GM retrofitted all Z28s with harder durometer bushings. The underside of the car was a right constellation, gashed and gouged like Beirut, like some dervish had gone absolutely ape with a fire ax and a ball peen hammer.
Yeah, just another drag test back when drag tests really were.
Author Mini Bio
Ro McGonegal began in this business back in 1968. He’s been editor of Car Craft, Hot Rod, and Chevy High Performance. He’s a wealth of old-school knowledge and his stories from “back in the day” are epic.