Charlie’s Smokey Mystery

How a New England Chevy Fan Ended Up With An Ultrarare NASCAR Exhaust System

By Steve Magnante – Photography by Charlie Sanden

Today, everybody and his uncle owns and uses a Smartphone with built-in camera capability. It’s been said that not a second goes by without at least a thousand digital pictures being taken all over the globe. But it wasn’t always like this. Back in the ’60s, photography was still considered an artform; many families didn’t even own a camera, let alone car people. That’s why it’s extra special when vintage car enthusiast pictures surface today.

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Though born in Pennsylvania, Charlie Sanden lived his adult life in West Springfield, Massachusetts, where he worked as a combustion research engineer for aircraft engine manufacturer Pratt and Whitney. This April 1968 picture shows Charlie at the wheel of his Mystery-enhanced 427 Impala SS. The black rubber boot on the steering column suggests the car was factory built with a column-shifted three-speed manual transmission. Charlie added the floor-shifted four-speed manual transmission with the 427 swap. The column shifter rules out the possibility Charlie’s Impala was born a 409.

In this story, let’s examine a handful of color prints taken by Chevy fanatic Charlie Sanden in 1967. Most significant, Charlie was friends with the late, great Smokey Yunick, whose Best Damn Garage In Town was a Daytona Beach, Florida, legend. If you didn’t know, Yunick was one of NASCAR’s pioneers, working closely with Hudson, Pontiac, and Chevrolet in the 1951–1967 time frame. The unifying bond between Charlie and Yunick was the fact both attended the same Chicago-based engineering school, though not at the same time, as Yunick was older than Charlie.

Dated September 1967, this is one of several photos Charlie took of the Impala’s Corvette-sourced Mark IV 427 engine. Though the limited-edition Mark II and mass-produced Mark IV big-blocks differ in many ways, they share the same exhaust manifold bolt pattern, so the slick manifolds were a bolt-on deal. The four-into-one collector was fabricated by Charlie to snake past the Impala’s stock front suspension. The medium-blue engine paint is an interesting departure from the expected Chevy Orange.

Nonetheless, beginning around 1964, Charlie made regular winter pilgrimages from chilly Massachusetts to balmy Florida to attend the Daytona Speed Weeks where he cheered Yunick and his various teams’ efforts in stock car competition. It was during the 1966 visit (most likely) that Charlie managed to obtain some cast-off exhaust manifolds and a cowl induction system from Chevrolet’s abortive 1963 427 “Mystery Motor” and Z11 campaign. And it’s pictures of those ultrarare GM racing parts that stimulated the creation of this article.

The driver side manifold is quite different in how the runners gather together in a square rather than inline, undoubtedly in order to clear steering linkage. Both manifolds share a common 12-12-62 casting date. More on this in a moment. Again, the four-into-one exhaust head pipe extension was fabricated by Charlie to fit his Impala. The extensions designed by Chevrolet were sized so each primary runner measured exactly 40 inches from the exhaust valve to the mouth of a huge 4-inch collector pipe. For reasons unknown, Charlie was only able to get the cast-iron parts and not the lower halves.

The 1963 NASCAR racing season was poised to be a great one for General Motors. Pontiac 421 Super Duty engines were at peak tune and Chevrolet rolled out a new V-8 engine design intended to replace the asthmatic 348/409 and Z11 427 W-series. Dubbed the Mark II V-8 program by those deepest inside GM engineering circles, the result looks an awful lot like the 1965 Mark IV 396 big-block. But that’s only partly accurate. While major elements of the Mark II showed up on the Mark IV 396 and its 427-, 454-, and 502ci siblings, very few parts were interchangeable. In fact, the Mark II’s 2.50-inch crankshaft journals (taken from the 348/409 W-series) were smaller than the 2.750 size used in the Mark IV, and surprisingly the Mark II used two-bolt main bearing caps. The Mystery Motor nickname stems from the tight-lipped approach taken by Mark II race teams when approached by the press for details of their new wonder weapon.

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Seen from the front, Charlie’s collector tubes splay outward despite the fact the Impala’s frame and suspension are able to accommodate more conventional tubing with an inboard trajectory. Charlie routed his pipes to appear suddenly from behind the front tires. We’d guess his goal was to show off the exotic plumbing. We sure would! The circular core plugs on the ends of the cylinder heads are not present on 1963 Mark II Mystery 427 heads, which are also not interchangeable from side to side.

When the Mark II 427 debuted at the 1963 Daytona 500, it was aboard race-prepped Impala hardtops fielded by Ray Fox, Rex White, and … Smokey Yunick. It is believed that 26-48 complete Mark II 427 race engines were made available to these race teams. Junior Johnson (driving for Fox) and Johnny Rutherford (driving for Yunick) dominated both 100-mile qualifying races in their Mystery 427 machines, with Johnson surpassing the 168-mph mark on some practice laps, 7-10 mph faster than 1962 records. In total, five 427 Mystery-powered Chevys qualified for the 1963 Daytona 500. Ford, Pontiac, and Mopar drivers were outclassed, their inline-valve wedge-head engines incapable of processing gases as efficiently as Chevrolet’s new canted valve “semi-hemi.”

Mounted in the Impala’s engine bay with room to spare, the 427 (either variety) isn’t much larger than a 409. The cowl-induction air cleaner unit is from a 1963 Impala Z11 application. The small fleet of 1963 Impalas built for the Daytona 500 used a similar cowl-induction system but with a taller housing and adapter neck with different surface details (see photo 14). Notice the Sun tachometer trigger box mounted above the brake master cylinder.

But things didn’t go so well. At the end of the big race, newspaper and magazine headlines read “Fords Sweep Daytona 500” as the first five finishers were Blue Oval Galaxie “Scatbacks” packing aforementioned 427 wedge power (Tiny Lund was the winning driver). Even worse, a month after the February 24 Daytona 500 event, General Motors officially quit sponsoring race cars and race teams. Fear of anti-trust legislation was behind The General’s decision to “reduce its corporate profile anywhere it could.” Apparently, some hard-nosed politicians had been eyeing GM’s marketplace domination with an eye toward breaking up such monopolies in the name of fair trade. At the time, GM cars accounted for more than 50 percent of all domestic new car sales (53.9 percent in 1962 and 53.2 percent in 1963).

The driver side Mystery manifold fits without hassle. As with the Pontiac 421 Super Duty, Ford 406/427, and Max Wedge Mopar, NASCAR’s prohibition on tubular steel exhaust headers (until 1964) forced Detroit carmakers to create some downright beautiful cast-iron manifolds. Charlie’s decision to paint the aluminum alternator black is unusual. The deep groove pulley suggests it is likely the original unit from the L71 Tri-power Corvette engine donor.

The feared government trust-bust never materialized but GM race-vehicle programs that were nipped in the bud included Pontiac’s 421 Super Duty Tempest/Swiss Cheese Catalina program, and from Chevrolet the lightweight Z11 Impala, Grand Sport Corvette, FIA Nova fastback with Corvette independent rear suspension, and, yes, the 427 Mystery Motor. But here’s the rub. Just because GM wasn’t out in the trenches with factory-built and assisted race machinery, privateers kept the ball rolling quite successfully despite continued factory participation from Ford and Mopar.

On the passenger side, the inline exhaust ports easily sandwich between the engine and wheelhouse. Though the Mark II Mystery 427 used the tubular aluminum spark plug heat shields first, they also appeared later on high-performance versions of the Mark IV 396 and 427. Charlie replaced the factory steel fuel line with copper, seen feeding the high-volume metal canister AC fuel filter from below.

As for the Mystery motors, they were quickly forgotten as the solid-lifter 409 resumed top showroom horsepower billing in 1964 and through mid 1965, when the production version of the Mark II, the similar-but-not-the-same Mark IV 396 made its big debut in April of that year. For Yunick’s part, it is said that thanks to his warm friendship with performance-minded GM executives like Vince Piggins (who he knew from their shared efforts for Hudson’s race team a decade earlier), factory requests for the return or verified destruction of “obsolete” engineering parts were ignored. In fact, Yunick was something of a pack rat, as proven by the astonishing stash of factory prototype parts–including aluminum block 327s and the remains of XP819, an experimental rear-engine Corvette from 1964–that were sold at his first public auction in 1986.

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This close-up of Charlie’s Z11 air cleaner shows the rubber seal fitted between the cowl plenum flange and air cleaner duct to allow engine movement. The Z11 lightweight Impala program was meant strictly for drag racing. By all accounts, the Mark II 427 Mystery engine program was targeted at NASCAR first and foremost, though a few leftover engines ended up in non-factory (independent) Chevelle and Nova dragstrip match racers in 1964. Chevy built just 57 Z11 Impalas and perhaps 20 over-the-counter Z11 conversion kits before the program was canceled by the March 1963 anti-racing edict. Note the presence of a functional heater unit. Charlie is said to have driven the car year-round. Factory Z11s were strictly heater-delete for reduced mass.

Getting back to the story of Charlie Sanden; it was probably during his 1966 visit to Yunick’s Florida lair that he managed to obtain some cast-off goodies from the 1963 Daytona 500 Mystery 427 program. As evidenced by a handful of color photographs taken by Charlie in 1967, it’s clear that he owned a white 1962 Impala Super Sport hardtop that he transformed into a big-block–powered street stormer. At first glance, the gleaming white iron exhaust manifolds and huge Z11 cowl induction air cleaner unit imply they’re attached to one of the handful of Mark II 427s trusted to Yunick. That would be a mistake.

This winter time shot proves Charlie initially enjoyed his 427 Impala year-round before putting it into storage during the early ’70s. A close look at the front fenders reveals the crossed flag “V” emblems common to 327-powered Impalas. The evidence of a column-shifted three-speed manual transmission seen in an earlier picture rules out 409 origins. The massive canister mufflers–also painted flat white–were from a Chevy C60 5-ton truck application. They’re angled inboard to follow the Impala’s unique X-frame.

The fact is–the big-block engine to which the exotic intake and exhaust parts are affixed–a 1967 vintage 427 taken from a 435hp Corvette Sting Ray, it’s not a 1963 Mark II Mystery 427. But it’s still a pretty special 427 engine. This was discovered after Charlie’s death in 2016 when Charlie’s heirs requested family friends Bob Polverari and Barry Kuhnel examine the car before its sale to settle the estate. The block’s machined identification pad reads T1227JE, the JE suffix code matching it to a 1967 427/435 triple-carbureted Sting Ray L71. That alone makes it pretty special.

The five-slot Rally wheels with large cone center caps arrived in 1968 and were an instant hit with swappers like Charlie. Notice how he re-painted the argent silver rims black to better highlight the bright red front and rear brake drums. Charlie also applied flat white header paint to the protruding exhaust tract for full impact.

In fact, Polverari (himself a local Modified stock car racing legend and five-time track champion at Riverside Park Speedway in the day) was close buddies with Charlie back in the ’60s and clearly remembered how excited Charlie was to install the Mystery 427 exhaust manifolds and 1963 Z11 Impala cowl induction, making it the only engine of its kind in New England.

From the front, the oversized exhaust plumbing adds a menacing feel, as if the engine is too big to fit and bulging at the seams. We have no word on the black 1963 Chevy Biscayne, but knowing Charlie’s penchant for go-fast machinery, we’d bet it isn’t stock.

Once proper identification was completed, the exotic Impala was recently sold to an enthusiast from Worcester, Massachusetts, who fully understands the historic significance of the package and plans to leave it exactly as Charlie assembled it in 1967: complete with bright white header paint to attract full attention to its exotic exhaust system.


These chunky head pipe extensions weren’t included with Charlie’s Mystery manifolds, forcing him to make his own. They fed side-exit straight pipes on the NASCAR stockers. Where is this stuff today?
Another close-up from the Hot Rod story depicts the inner surfaces of both exhaust manifolds. 1963 was the last year that NASCAR mandated “stock” cast-iron exhaust manifolds. In 1964 they finally caved and allowed lighter, more efficient steel-tube headers, putting an end to beautiful factory iron like this.
This close-up from the Hot Rod exposé has significant relevance to the exhaust manifolds on Charlie’s car. In particular, the passenger side manifold shown in Hot Rod bears the same 12-12-62 casting date. With only 26-48 complete engines made, just 52-96 copies of each manifold were needed. It is possible the iron foundry supplying them to GM did the job in one day to get it out of the way for the much larger lots it was used to. We must wonder if other existing Mark II exhaust castings share this same date. Another nifty detail is the integrally cast part number which reads “0-224672.” The “0” represents a pre-production part in GM parlance. The same number appears on Charlie’s passenger side manifold. We’re all thankful Charlie resisted the temptation to grind away “unsightly” characters as so many car owners do in seeking the utmost in sanitary presentation.
More pages from Hot Rod’s nine-page exposé on the Mystery 427 claim that the new big-block was 45 pounds lighter than the Z11 and only 49 pounds more than a fuel-injected 327 Corvette V-8. Speaking of Vettes, two 1963 Z06 Sting Ray coupes were re-fitted with Mystery 427s by Yunick and Mickey Thompson for the 250-mile American Cup Challenge sports car race on the Daytona tri-oval, February 16, 1963, one week before the Daytona 500. One finished in Third place with Bill Krause driving. These were the first big-block Corvettes, the Krause car being resurrected by Chevrolet collector Tom McIntyre in 1983 with a 427 Mystery engine supplied by Yunick.
Here’s the May ’63 Hot Rod magazine article in which author Ray Brock pulled the lid on the Mark II 427 for the first time in print. Though Brock repeatedly referred to the engine as the “H-D 427” that name didn’t stick. Brock exploded some of the scuttlebutt surrounding the engine, such as: “Some of those early rumors about Chevy’s new V-8 and how they proved out were; Conventional-type block with head surfaces perpendicular to the bores (true), an overgrown 327 (false); overhead camshaft (false); odd valve layout (true); hemispherical chambers (false); and, fantastic amounts of horsepower (true).” We love old magazines for stuff like this.
This photo is dated October 1967 and shows the Impala riding on stock steelies and baby moons. Here, the C60 Chevy truck mufflers haven’t been painted and better show off their nearly circular cross section. It’s likely Charlie used them on advice from Yunick, who knew his way around the parts bin when seeking above-average parts. With their huge internal volume, these mufflers likely dulled exhaust noise without adding back pressure.
This close-up of Charlie’s Z11 air cleaner shows the rubber seal fitted between the cowl plenum flange and air cleaner duct to allow engine movement. The Z11 lightweight Impala program was meant strictly for drag racing. By all accounts, the Mark II 427 Mystery engine program was targeted at NASCAR first and foremost, though a few leftover engines ended up in non-factory (independent) Chevelle and Nova dragstrip match racers in 1964. Chevy built just 57 Z11 Impalas and perhaps 20 over-the-counter Z11 conversion kits before the program was canceled by the March 1963 anti-racing edict. Note the presence of a functional heater unit. Charlie is said to have driven the car year-round. Factory Z11s were strictly heater-delete for reduced mass.


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