1970 Chevrolet Corvette ZR1 - Barn Stormer

Seattle's Dan Pepper, An Alert And Lucky Corvette Enthusiast, Found Himself A Spectacular Barn Find, A '70 ZR-1

Iain Ayre Aug 30, 2009 0 Comment(s)
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The ZR1 as found, after collecting dust in Darrell's garage for many years.

The age of spectacular barn finds is mostly over: there aren't any more Le Mans Bentleys still sleeping under inches of dust in English barns. For the alert and lucky Corvette enthusiast, though, there are still a few gems hiding out there, and Seattle's Dan Pepper tracked one down.

Dan Pepper has been a Corvette nut since 1970 when he first got a ride at the age of six in a brand new Laguna Grey coupe. Like watching the Apollo 11 moon landing on TV the summer before, that experience is still a vivid memory. Over the years, he pined for a C1 or C2, and finally bought his '66 427/390 Coupe, which is unrestored and has earned NCRS Top Flight recognition.

An additional "ordinary" Corvette was required to keep the miles low on the '66, but the C2 market was going through the roof, so Dan started looking for a nice original chrome-bumper C3 to use as a driver. He found an ultra-clean low-miles '69 350/350hp coupe in Monaco Orange over black vinyl. The '69 coupe got him interested in the C3 chapter of Corvette history, and he decided a nice big-block would round out his collection. Perhaps a 435hp tri-power car, or possibly one of the rare LS6 '71 Corvettes with aluminum heads...the search was back on.

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The Shark in its purer forms can hold its head high in any Corvette company, and the ZR1 is about as pure as it gets.

During a protracted and ultimately unsuccessful bidding war over a survivor-quality '71 LS6 Coupe, he got to know the LS6's owner, retired Boeing engineer Brian Graebel. While Brian was commiserating with Dan over losing the bidding contest and thanking him for inadvertently helping to jack the final sale price up to a very useful sum-Dan kept bidding right up to the edge of risking his kids' college fund-he happened to mention a friend and co-worker who owned a '70 ZR1.

So what are the chances that a guy who owned a very rare car like a '71 LS6 Corvette worked elbow-to-elbow with another guy who owned an even more rare '70 ZR1? It sounded unlikely. However, Brian drove Dan over to meet "Mr. ZR1," Darrell Boettger, whose garage door was rolled up to reveal a weary-looking Bridgehampton Blue Corvette Coupe hoisted up on a 4-post lift. It was coated in dust and not an impressive sight. Dan spent the next two hours poking about with a flashlight, clipboard and digital camera, although Darrell wasn't interested in selling the car.

Darrell had originally thought it was just an LT1 with an M22 transmission and a 4.56 posi rear end. After buying the car and graduating from Purdue University in 1979, he took a job at the Boeing plant in Everett, Washington, as a propulsion engineer, and towed the Corvette behind his Camaro from Indiana to Seattle in the middle of winter. The windshield got cracked as he jackknifed on an ice patch in NE Oregon. Luckily there was no other damage (other than to the Camaro's driver seat upholstery).

A new career, bride and baby mostly elbowed the Corvette aside, but in the mid '80s Darrell went to overhaul the brakes and took the old front brake pads to a local Corvette shop. The shop owner, well-known west coast SCCA racer Rick Stark, asked him what the dual-pin pads were from and explained that those J56 brakes were only available on the ZR1 in 1970. Darrell then realized the car might be a ZR1. Trips to Bloomington Gold, and correspondence with ZR1 experts regarding engine pad, date codes, tank sticker and the car's unique configuration, confirmed that the blue coupe was one of the 25 ZR1s produced in 1970. Dan's research and photos further confirmed that this car was a truly rare piece of Corvette history.

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The '70 and '71 ZR1s were fitted with the base-engine type metal fan shroud. The '72 cars were shroud-less. There is one other item often overlooked when reviewing the HD radiator/cooling system on the ZR1: the HD radiator used a modified (widened) radiator core support.

Dan still wanted the ZR1 very badly, and he would get together with Darrell and Brian every so often to talk cars, drink microbrew and reminisce about "the good old days." Every session, Dan gently nudged Darrell towards selling him the car. Finally, Darrell agreed, but on two conditions: first, that it would be restored to NCRS specs, and second, that it would be replaced by another C3 as well as a major roll of Franklins. Darrell now owns Dan's '69 Monaco Orange Coupe, and "Ol Blue" is now garaged alongside Dan's '66 big-block.

Dan got the ZR1 home and instantly started poking around the dash, looking for an interior order copy. The tank sticker was very faded and hard to read. He was hoping that the order copy, often stuffed behind the dash between the tachometer and speedometer, was still there. It was, but somebody else had found it first. It was now part of an ancient mouse's nest. However, the reassembled scraps of paper supported the car's genuine identity and matched the spec: ZR1 370HP Special Purpose Engine Package, M22 HD Transmission, F41 Special Use Suspension, J56 Heavy Duty Brake Package, tilt/tele column, 4.56:1 Positraction and NA9, the one-year-only California-required Evaporative Emissions Control System. The latter, along with the printed dealer number "183," suggests the ZR1 was originally purchased in California, either at Guaranty Chevrolet in San Diego, or F. H. Daley Chevrolet in San Leandro.

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They appear to be leftover pieces that were modified originally for the '68 and '69 run of L88s. The tag on the radiator confirms the radiator is the correct heavy-duty type and the date.

Dan is a member of NCRS, and intends to restore the car to factory specs, but he's in no hurry as he's enjoying being able to drive the car without being afraid of a little wear and dirt. The odometer reads 39k miles, and that's quite likely correct as the 4.56:1 rear end ratio is a bear to drive on the freeway, with 3800 RPM for 70mph, although the low rear end makes top fun out of short blasts around town. A speedo gear reduction box fitted between the transmission and speedometer cable hook-up was required on all cars with 4.11:1 and shorter gearing, and that's still present and works fine.

The interior is mostly original but rough, with cracked door panels and non-original front carpet. The Mexican-style blue velour seat inserts were fitted in the 1970s before Darrell bought the car, and the Hurst shifter is another '70s addition. The rest of the interior is stock, down to the radio block-off plate.

The car has had one lacquer repaint in its original Bridgehampton Blue and if you look close, you will notice the original LT-1 hood stripes were not reapplied. Dan said "A ghost image of the original hood stripes can be seen under the paint when the light hits it just right. Who knows-maybe leaving them off was an attempt at being stealthy-or to save a few bucks. I have a stencil kit and decals, and have contemplated re-applying them prior to the repaint/restoration just so it has all the LT1 cues. I've left them off for the time being so the car might be recognized by a previous owner or anyone else who might remember it the way it was back in the '70s. Eventually it will be restored to factory standards-complete with stripes and decals." Original paint remains in the doorjambs, along with the blue GM certification label and factory trim tag. The car was judged at the 2007 NCRS Regional Meet, as a way to "benchmark" its condition prior to restoration. The most minute details continue to be thoroughly photo-documented, to be sure nothing is missed upon restoration and reassembly.

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The interior is still an inviting place, although some of the plastic trim is showing signs of age and use. A while ago, back when velour was trendy, it was cheap to drive down to Mexico to get good quality re-upholstery work done at a good price. Seat panels look tacky now, but were a smart move at the time. The LT-1 tach redlines at 6500 rpm and at some point in the car's history, someone installed a Hurst shifter. Also notable is the radio delete plate instead of a radio. The stock antenna hole in the body was also filled in at the factory.

Researching C3 ZR1s has become a passion for Dan, and he has uncovered details on other authenticated ZR1s that confirm the authenticity of his own car and also provide new perspectives into how these cars were assembled. Parts date-coded well beyond the typical six-month build window are common on the heavy-duty racing parts associated with these cars, because ZR1s are essentially an L88 prepped chassis with a slightly modified LT1 engine. For that reason, it's no wonder that some L88 parts with 1969 and earlier dates are found on these cars. If there was one thing that Zora Arkus-Duntov was good at, it was utilizing whatever he had on hand to make a car perform better and faster-so he raided L88 parts bins from the 1968 and 1969 L88 production run to build what he is quoted as calling his "...last great white hope for Corvette racing ecstasy."*

Dan is hoping that the publication of the story of this car will help bring forward anyone who can add to its history. Based on the presence of NA9 California-only emissions gear and the 183 dealer number, he wonders if the first owner was a military serviceman who took delivery in California and then brought the car "home" to Indiana, Illinois or Ohio. The third owner from whom Darrell bought the car is a doctor who also didn't realize the rarity of the car, and recalled that the fellow from whom he bought the car was possibly a lawyer who dabbled in buying and selling performance cars. That fellow told the then med-student he was the second owner.

Based on the choice of the 4.56:1 Positraction and the homemade tow-bar brackets, the car seems likely to have seen some racing action. The low final drive ratio suggests that auto-crossing, drag racing or hill climbs were probably the events of choice.

Dan has found that driving this car is a unique experience compared to other mid-year and C3 Corvettes. The car feels incredibly well balanced compared to its big-block brothers. The suspension is very firm yet supple, and allows the car to remain flat through corners with little lean, yaw or roll. The suspension offers a hint of understeer that can be easily managed with the throttle. These characteristics allow the car to be driven to the edge of adhesion and beyond, then easily brought back into line. The car's inherently peaky LT1 engine and lightweight flywheel provide instant gratification that's compounded by the 4.56:1 posi-traction.

The ZR1's rip-saw solid-lifter exhaust note, whining M22 transmission and low gearing cause the car to sound like an old hay truck on methamphetamines. As Dan says, it's pure bliss...

Have you ever seen this car racing? Have you any idea who the first owner was? If this story jogs your memory, talk to Dan at 1970ZR1@corvettes.com. You can also follow the restoration as Dan will document it in detail on his website, www.corvettes.com.

*(quote directly from Jerry Burton's biography of Zora Arkus-Duntov).

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ZR1 Factoids
The ZR1 "Special Purpose Engine Package" cost $968.95 - almost 20% the base cost of the car. The package consisted of the LT1 engine with a lightweight flywheel and high-torque starter; M22 HD close ratio four-speed manual transmission; F41 suspension comprising special 89lb front springs, 121 lb rear springs, matching shock absorbers and .75" front stabilizer bar; J56 HD Brake Package with power assist, dual-pin front calipers and semi-metallic brake pads; HD (high-capacity) Aluminum radiator with overflow tank; HD Positraction rear end; and various parts left over from the previous model year's high-performance parts bins. The only "options" available when ordering the special-purpose engine package were the deluxe interior and tilt/telescope steering column. Power windows, power steering, air conditioning (like all LT1's), radio, rear window defrosters and PO2 wheel covers were not available with RPO ZR1. The C3 ZR1's are essentially an L88-prepped chassis, fitted with a slightly modified LT1 rather than the 430hp 427.

* The Special Purpose Engine Package was a different assembly from the standard LT1 engine available in its civilian brethren, hence the different suffix codes assigned to call out the non-standard parts required. Although the internals, intake and exhaust were identical to the standard LT1, the CTV suffix code in '70 (and the CGY in '71 and CKZ in '72) were fitted with a 10.5" light weight L88-style flywheel and corresponding #403 bellhousing as well as a high-torque L88 ('69 coded & dated) starter with aluminum nose.

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A powerful small-block may not have the grunt of the bigger Corvette engines, but nor does it carry massive front-end weight: the whole car is significantly better balanced. The current carb is temporary but a date-code-correct smog system (pump, hoses, clamps, etc), 1100884 alternator and corresponding very rare Holley 4489 NA9 carburetor (California LT1 cars only) is restored and ready for installation.

* The ZR1's low build numbers prompted the use of small batches of special heavy-duty parts. These parts are often date-coded exactly the same, even if the build dates of the cars are months apart. This has turned out to be a dependable way of authenticating purported ZR1's.

* The ZR1 was the last GM production vehicle to come with the factory disclaimer warning: "Not intended for normal driving situations."

* The 1970 model year production was postponed until January of that year making it the shortest model year run of the Corvette in history.

* The ZR1 Engine Package option was not mentioned in GM literature until well into the model year run. This suggests that those who ordered the cars were either connected with organized racing, or knew the right people to place the orders.

* There were reports that early cars featured the L88-style cold air induction hoods, but this has never been substantiated.

* A few of 1970's performance-minded Corvette buyers most likely ended up with a ZR1 when the 465HP LS7 Corvette engine option was pulled from production at the last minute. The ZR1's were the next "hottest" Corvette available if you intended to go racing.

* The ZR1 used a different (beefier) shock mount than other, non-F41 equipped Corvettes.

* All ZR1 rear deck panels were originally drilled for a radio antenna because most Corvettes were ordered with radios. The ZR1s and "radio delete" cars had the hole filled on the assembly line.

* In an attempt to sandbag horsepower numbers to obtain lower insurance ratings, the LT1 engine was rated at 370hp. It's generally accepted the solid-lifter mouse motor's factory output is closer to 400hp, and can easily be increased by adding headers and a little performance tuning.

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