No Limits Magazine from Wild About Cars
Profiling High Performance Cars and the Golden Era of Detroit Iron
- We Bring History to Life and Put Resources in the Hands of the Enthusiast -
Monday March 24, 2014
Chevy "Mystery" 427, '69 Mach 1, '68 Javelin, and '69 Olds W-31 Tests, '87 Trans Am Convertible, Marty Schorr Touted - and More!

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Chevrolet Big Blocks - Part Two: the Mystery 427 Sets the Stage
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The Mark II Chevy Big Block

This is one of the two copies known - it is the display engine
located at the GM Heritage Center .

Mark II Head Top View

This shot of the Mark II head shows the familiar layout of
the canted heads, and the oval exhaust ports used.
The heads were smaller and lighter than the Mark IV .

by Wild About Cars Staff - reprint with permission only.

Part Two - The "Porcupine" - more 409 than 396

The "Mystery Motor" or "Porcupine", as it was called back then, was NOT an early production Mark IV 396-427. It was a 409-427 with special heads designed for "high speed" (rpm) operation on the NASCAR super speedways such as Daytona. Of course, the lessons learned with the Mystery Motor convinced Chevrolet, that it could be revamped and delivered as Chevrolet's new big block.

But first, we need to understand that GM's 1963 racing ban hammered Chevrolet's plans for competition in NASCAR and NHRA - not to mention SCCA, FIAA and USAC. As early as 1961 the brass knew that the 409 cylinder head design was at a dead end, and that a "wedge" engine had its limitations, but Hemis needed complex valve train and the heads were huge. precluding fitment in the Corvette. They also knew that larger cubic inch engines would be needed to keep the heavier Corvette competitive in sports car racing.

Chevy had an ace in the hole and they knew it. The stamped steel rockers sat on an individual pedestal and did not use a single rocker shaft to hold the rockers in place. In a huge inspiration, they recognized that they could cant the intake and exhaust valves toward the port like a hemi AND even twist it so that it lined up with where the port had to be - allowing for ultra high-flow numbers.

What this arrangement also allowed was hemi-like flow with a relatively narrow head - assuring that the motor would fit in the new C2 Corvette, then due out in 1963. That the Mark IV appeared in the Corvette in 1965 first was no accident.

Mystery Motor Specs:
The Mystery Motor was a special casting designed to allow the fitment of the heads, but was similar in specification to the Z11 427 designed for drag racing. It had its own designation, "Mark II".

Mark II engines carried the casting number of "0-217199". The "0" denotes a pre-production casting. Also cast in the block is 9-13-62 - the date of Sept 13, 1962 in standard short abbreviated form - which is the date the blocks were cast.

In a pre Daytona dyno test, the 427 Mystery Motor made 620 hp with a single Holley on a 180 degree high rise aluminum manifold. There were 4 different intake manifolds developed for the engine. All were 180 degree design. Smokey Yunick stated the best of the 4 designs was that with casting number 0-232166. . . .

To Read more about the Mark II Mystery Motor - Click HERE!

To Read HR Magazine's in-depth look at the Mark II Motor - Click Here!


More Stories at Wild About Cars and the Auto History Digital Documents Library
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1962 Ford 406 Test 1969 Mustang Mach 1 Road Test

Car Life gushed about the Mach 1 in their March 1969 issue: "are you ready for the first great Mustang?" They loved it's acceleration, handling and ride. saying, it as the "quickest standard passenger car through the quarter mile". And it was quick, running a 13.9 @ 103 - and this was an automatic equipped car. They closed with, "An enthusiast will find the Mach 1 a rewarding car. . ."

Click here to read the 1969 Mach 1 Test!

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1968 Javelin 343 Test 1968 Javelin 343 Intro and Road Test

Hot Rod called the Javelin 343 an "American Dream" - and to AMC it was. HR liked the car's handling and interior comfort, but were less than enthused with their car's lackluster performance. (This was rectified with later Javelins with the 343 and by the addition of the 390 mill). They liked the brakes, beefy construction and the anticipated 390 - but in December 1967, they were unsure if the market would accept it. Time tells us that it and the AMX would be - big time.

To read the rest of this1968 Javelin 343 Test - Click HERE!

1969 Olds Cutlass W-31 Tests 1969 Olds Cutlass W-31 Road Tests

Both Car Life and Car and Driver tested the W-31 in 1969 - one was an auto trans car and one was a 4-speed. Regardless - both magazines were overjoyed and stunned with the little Cutlass's performance. CL said "somebody has taken a heavy car with a mid-range engine and made it perform with supercars." And perform it did - the auto car ran a 14.9 @ 96 and the stick car ran 14.5 @ 97! Car and driver said ". . . those in the sporting sedan business had better take note."

To read these 1969 Olds Cutlass W-31 Tests - Click HERE!

1987 Shelby Mustang Test ASC Firebird Convertible Modern Muscle - 1987 Pontiac/ASC Firebird Conversion Info

Few may remember that GM was caught flatfooted when the Mustang GT was available with a drop top and F-body Camaros and Firebirds were stuck with T-tops as their open air equivalent. This did not sit well with many Chevy and Pontiac owners who discarded their loyalty and bought the 'Stang. Well, GM commissioned the famous concept car maker to build a drop top and in 1987 you could get your open air motoring in a Firebird . . .

To read the 1987 Firebird Conversion Brochure - Click HERE!

Kyle Busch Wins California 400 Race news - Kyle Busch Takes an Exciting California 400!

In a race that saw tire problems turn the contest upside down, Kyle Busch won Sunday's Auto Club 400 in a green-white-checkered-flag finish that took the fifth NASCAR Sprint Cup Series event of the year six laps past its scheduled distance. Able to keep Larson behind him, Busch crossed the finish line .214 seconds ahead of the 21-year-old, who had won the NASCAR Nationwide Series race one day earlier . . .

Click here to read more at the Autoweek Racing website!

Dean Jefferies Porsche is saved.
Featured Story - Marty Schorr a Ford GT Owner - Likes to Know He Could Drive 205 MPH.

"I bought mine 2½ years ago. The first thing Ford GT owners tell you when you buy one is that you need a comfortable chair to put in your garage, so you can sit and stare at the car." And Marty knows what he's talking about, having been the editor of Cars Magazine and involved in the auto industry since the 60s. The story in the Wall Street Journal is short - but if you want to see Marty's knowledge and expertise check out our Magazine Archive or just look thru our Tech Section's Road Tests to see Marty's work . . .

CLICK HERE to see the Wall Street Journal article on Marty.

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