You read about it in Car Craft and Popular Hot Rodding. Maybe you saw one at the drag strip and or the local cruise. Dealers didn't know much about it. In fact, it wasn't even listed in the showroom brochures or the standard dealer sales albums. "It" was RPO L78. Although it was a total mystery to most dealers, those who knew the magic option code could buy the meanest, most powerful big-block in the Chevelle arsenal.
Unless you lived near a Chevrolet performance dealer like Yenko, Berger, Gibb, Rosenthal, Indianatlantic or Rathmann, the chance of finding anL78 on the showroom floor was somewhere between slim and none. You had to know how to get your mitts on a Special Product Order form and fill out the right information, then get the dealer to order it for you. You gave him your deposit and then you waited six to eight weeks for the hauler to arrive with your L78 Chevelle.
What was the L78? It was 375 hp wrapped up inside a 396-cid engine. There was only one other option that made the L78 look mundane, and that was the L89, which parked a set of aluminum cylinder heads atop the iron-block 396, but retained the same 375hp rating. The L78 was an expensive option ($252.80), but the L89 was even more ($647.75). As enigmatic as the L78 was in the showroom, thanks to magazine coverage, 9,486 L78 Chevelles were ordered in 1969. The RPO Z25 Super Sport package was now an option (RPO Z25) on any Chevelle V-8 hardtop or convertible. Along with specific emblems on the grille, front fenders and the blacked out taillamp panel, the SS package also featured a domed hood and power front disc brakes. Sales of the 1969 SS option were strong, with 86,307 rolling out of dealers' doors.
Part of the L78 SS396 package was the F41 heavy-duty suspension. The F41used firm springs, a large stabilizer bar and firm shocks up front, along with a four-link coil spring rear configuration with firm shocks. The rear lower control arms were boxed by a plate welded across the sides for reinforcement. A rear stabilizer bar was bolted to the inner sides of the control arms. The upper arms were braced to handle the massive torque of the L78. The optional 14x6 sport wheels with F70x14wide oval bias belt tires put a wide footprint on the ground, however they'd go up in smoke when the wood was laid to the L78.
The L78 396 had a 375hp rating measured at 5600 rpm and peak torque of 415 lb-ft came on at 3600 rpm. The L78 was fitted with aluminum impact extruded 11.0:1 domed pistons, with drop forged steel rods weighing 27.84 ounces. Down in that beefy four-bolt main block was a forged steel crank. The mechanical valvetrain used 1.70:1 rockers and a cam that measured 316 intake and 302 exhaust, with an overlap of 80 and a lift of .5197. The iron-head L78 shared the same valves with its aluminum head L89 sibling-- 2.195-inch intake and 1.845-inch exhaust. A Holley four-barrel with 1.686 primary and secondary throats was fitted to a dual-plane aluminum intake. Hefty cast-iron exhaust manifolds led back to dual exhausts and an optional dual-chambered exhaust (the best $30 option you could order) and then out to 2.0-inch pipes. Not only was this system more efficient, it was one of the sweetest sounding stock exhausts on the street.
Transmission choices for the L78 started with the standard three-speed manual and two four-speed manuals, either the M20 wide ratio or the M21or heavy-duty M22 close ratios. While the rest of the industry was installing Hurst shifters, Chevrolet stubbornly insisted on using Muncie shifters and linkage. Popular Hot Rodding magazine noted, "The Muncie linkage wouldn't go into second on three out of four tries over 15attempts. The linkage was horrible." An 11-inch clutch was standard.
For the first time, Chevrolet offered the M40 Turbo Hydra Matic three-speed automatic transmission with the L78. For the M40, the standard shifter location was on the column. When the optional console was ordered, the shifter moved to the floor. Astern was a heavy duty differential with 8.875-inch rear and standard 3.55:1 ratio, with optional gears ranging from 3.07:1 right up to a frame-twisting 4.88:1.
Just how fast was a stock 1969 L78 Chevelle right out of the box? Hot Cars magazine tested one in their February 1969 issue, recording a 14.07/101 mph. Popular Hot Rodding magazine tested a 1968 L78 SS Chevelle and found they could get the car down to the high 13s with just a set of Casler slicks. A better shifter and linkage, headers and a proper setup could whittle the L78's time down into the low 13s.
This 41,500 mile LeMans Blue 1969 L78 SS396 Chevelle is from the Rick Treworgy collection in Punta Gorda, Florida. Rick has a preference for the fastest factory Chevys, and his '69 L78 SS396 is one of the hottest in his collection. It's also rather unusually optioned out. It has the RPO U14 gauge package, which placed the 120 mph speedometer in the left opening and a clock in the small center opening. The right hand opening contained gauges for oil pressure, fuel, battery and water temperature. They surrounded a small 8000-rpm tachometer with a 5700-rpm redline. The tach was down from the driver's line of sight and difficult to read.
When Rick's car was ordered, the buyer sprung for the gauge package but passed on a radio, opting instead to specify the RPO U57 8-track stereo tape player with four-speakers. Only 12,635 Chevelles were ordered with the tape player. The Parchment interior is fitted with the optional Strato bucket seats and console. Optioned out like Rick's SS396 Chevelle, it was hard to find a musclecar that combined performance and comfort better. It was Chevrolet's fastest Chevelle available without a COPO order. Nothing stood out from the pack like the 1969 L78 SS396.