The 1969 ZL-1 Corvettes
For a long time it was believed that only 2 of these Corvettes were built with the ZL1 engine and sold to the public (a total of 69 Camaros also received this engine). One was a Daytona Yellow car with side-pipes and the other was a Can-Am White t-top coupe with (what are now known as) black "ZL1" stripes. Adding the ZL1 option added over $4,700 to the price of the vehicle because a host of other options were required (or automatically included). Technically, the ZL1 was a $3,010 option that consisted of an assortment of aluminum cylinder block and heads on top of the $1,032.15 L88 race option.
Unlike popular belief, the engine option was actually widely available via any dealer, the only reason only a few were delivered was the high price of the option in comparison to the similar (on paper) L88 option. The added cost simply discouraged sales. The ZL1 motor was developed by Chevrolet with the intended purpose of racing. Therefore it was necessary for Chevrolet to produce it as a regular production motor to qualify it. But it is likely that without the efforts of Zora Duntov the engine would never have made it to production. Chevrolet produced the ZL1 motor as a RPO (Regular Production Order) option in 1969 only, and only available as a RPO option on the Corvette. Additionally there were 1969 ZL1 Camaros produced; but only as COPO (Central office Production Order) orders.
The ZL1 engine was as exotic of an engine that could have ever been developed given the parameters Chevrolet had to work with 30 plus years ago. The all aluminum 427 ZL1 was patterned after the cast iron 427 L88, but it wasn't merely just a change of the block casting material. The ZL-1 featured thicker walls and main webbing, along with dry sump lubricating provisions. The bottom end was four-bolt, with a forged steel crank and rods with 7/16 inch bolts, Spiralock washers and full floating pins. Pistons were even higher domed than the L88s, yielding a compression ratio of 12.5:1. Cylinder heads were also aluminum and featured open combustion chambers and round exhaust ports and 2.19 inch/1.88 inch valves, a configuration adopted by the L88 in mid-1969. The aluminum dual plane intake was topped by a 850 cfm Holley four-barrel (double pumper) carburetor featuring mechanical secondaries. The ZL1's solid lifter camshaft was radical (higher lift and different duration), so the engine could live in the upper revs.
Any 69 ZL1 is easily capable of 11s with any competent driver, and running on drag slicks, can easily run deep into the 10s. The quickest documented ZL-1 was a 10.89 @ 130 by Motor Trend in 1968. Some people thought it was 10.60 @ 132 documented by Motor Trend in Oct 69, but that was actually the same car with a prototype LT2 454 motor. (additional details of this can be found in "Classic Corvette, The First 30 Years" by Mike Mueller, Pages 313 - 319, 2003 edition, published by Crestline - MBI Publishing Co.) Zora Arkas Duntoff himself claimed 10.5 on slicks. As we talk about tires, please remember, this is 1969 technology. Slicks of that era were not as sticky as some of today's radials that we find on some sports cars. On top of this, the ZL1's top speed with stock gearing was close to 200 mph, and it could easily go beyond if the gearing was changed. According to a statement by Gib Hufstater (a Chevrolet developmental engineer) in a 1999 interview, "Tom (Langdon) built the engine, I built the car. He got about 710 horsepower out of it."
The white ZL-1 pictured above belongs to the Kevin Suydam Collection in Washington state. It is now restored to original showroom condition. Along with its ZL1 option are the J50 power brakes, J56 heavy Duty Brakes, F41 suspension, K66 Transistor Ignition, G81 Posi Rear Axle, M22 Muncie Four Speed, F70x15 Red Stripe tires, A01 Tinted Glass and Front Louver Trim. It has been Bloomington Gold certified and featured in many magazines and numerous books through the years including magazines such as Motor Trend, Corvette Fever, Vette Vues, Classic Auto Restorer, Corvette Quarterly, Vette, Musclecars, and hard back books such as Automobile Quarterly, Corvette-The Complete Illustrated History, Corvette-Americas Sports Car, and American Muscle to name a few.
The yellow ZL-1 pictured above is in the hands of a Corvette collector by the name of Roger Judski of Roger's Corvette Centre in Orlando, Florida. He purchased the car in 1991 for $300,000 at a federal government auction. It had been restored in the 80s in Houston, Texas and then sold to a private party. The auctioning of the car was a result of a seizure from Richard Joseph Lynn who was convicted of dealing cocaine and sentenced to life in prison with no parole. Judskiís plan is to keep the car for life and he doesn't drive it.
There is some speculation as to a third ZL-1 in the hands of a private owner but this has not been confirmed to our knowledge. In 1968, Chevrolet brought two ZL1's to the dragstrip for testing -- one red and one white. The Red ZL1, deemed the "Saturday Night Special" was equipped with an automatic transmission available from the L-88 and 4.88:1 rear end gears. Running 9" drag slicks, this car ran 10.89 @ 130 mph! And this run was driven by an automotive magazine editor, not a fully experienced race car driver. This same red car had the LT2 454 motor in it for the Oct 69 Motor Trend tests. Where has it been since? Has it been destroyed?
Update: This one recently came to my attention
Here's the related article from www.corvettefever.com:
In 1969, the horsepower wars were at full throttle with manufacturers building every car with the most horsepower they could back with a factory warranty. The Corvette factory race car joined the market in 1967 with the L88 option, and for the next two years the L88 continued the horsepower tradition.
Priced at $3,000 with the ultra-rare ZL1 option, this all-aluminum engine became the rarest and most expensive engine option in GM history. According to Chevrolet production records, only two Corvettes were built with the ZL1 option in 1969. While several owners have claimed to own a ZL1, only one has been able to prove it-until now. This is the true story of the second documented ZL1 Corvette.
John Maher of Leechburg, Pennsylvania, is a life-long racing enthusiast. His first new car was a '62 Lightweight 409 Biscayne from local dealer West Penn Garage. He paid for the car by match racing in the street.
Years later, through friend Don Yenko, John heard of Chevrolet's plans to support back-door racing efforts. Now a Pennsylvania State Trooper, John decided to jump in with both feet. He ordered a big tank HD 427 (a factory-disguised L88) Corvette in late 1966. John raced on the local quarter-mile dragstrip, autocrossed, and hill-climbed a few times, but mostly drove the Corvette on the street. He later sold the big-tank Vette to a friend.
In 1968, John ordered a new International Blue L88 roadster, again through West Penn Garage. After racing locally for several months, he traded the L88 in for a new ZL1. Most people had no idea L88 Corvettes existed, let alone the ZL1. John's friendship with Yenko was proving advantageous and his car order included the ZL1 engine, an automatic transmission, and the required optional equipment. John wanted this car specifically for racing.
After several months, John learned production was delayed due to the automatic transmission request. Eventually the car's sponsor, Gulf Oil, wrote to GM explaining why an automatic was necessary, and GM finally released the order. The car was produced December 1968.
John replaced the original ZL1 motor with an L88 engine (one of several) provided by Gulf Research and raced the car over the next several seasons. At the end of the 1972 season, the car was parked with the original engine installed.
In 1988, a racing friend of John's called and asked if he still had the orange ZL1. Tony Faulk of Corvette World in Greensburg, Pennsylvania, suggested John take the car, which had been parked since 1972, to the Corvettes at Carlisle show.
Finally, in 1989, John pulled the car out of his garage-but the engine wouldn't turn over. Upon removal and disassembly, the cause became clear. While parked, a mouse had built a home in a block cylinder. Luckily, John had other engines. He installed a fresh L88 and continued to race and show the car until 2002 when the head of a valve broke, locking up the engine.
Still wanting to race, John decided to have a fresh ZL1 engine built. An old friend, Jim Evanuak, built the ZL1 residing in the car today. The original ZL1 engine was also rebuilt and placed in storage.
John changed the lettering when the car was displayed at the National Corvette Museum since most of the old sponsors have long-since closed. The new lettering pays homage to the businesses associated with its restoration: Corvette World, Evanuak Performance Engines, Keddie Chevrolet, Kiski Valley Upholstery, Bill Andreko Resorations, and InSignOut.
Today the car appears much as it did when John was racing; he still drag races, autocrosses and exhibits.
John has held onto a copy of the original invoice and the original tank sticker that shows the ZL1 engine option and the M40 automatic transmission. With this original documentation, there is little doubt this Corvette is the real deal.
writer: Alan Colvin
photographer: Jerry Heasley, Mike Antonick