The 1963 Z-11 427 Impala

  The R.P.O. Z-11 optioned Impala was designed for one reason and one reason only... Racing. Cubic inches were climbing fast in '63 and the Z-11 427 Impala was Chevrolet's way of keeping up with Ford, Pontiac, and Chrysler at the track.

  The 427 was a modified 409 engine. The stroke was increased, special heads, valves and intake manifold were added. Fuel was supplied by 2-4bbl Carter AFB carburetors. A special cowl induction air cleaner was also used as shown below.

Z-11 427's came with painted valve covers. Some were orange, others were silver.

  This car was all performance and no frills. You wouldn't find a radio or even a front sway bar. Most Z-11's were ordered with the heater delete option and no sound deadner. Light and fast was the idea with this car and to help lighten it, the Z-11 came with an aluminum front nose and other parts. Hood, fenders, front and rear bumper, front and rear bumper brackets and braces, grill brackets, a 2 piece riveted fan shroud, grill filler panel and hood support catch were all made from light weight aluminum making the car about 300 pounds lighter than a similar 409 powered production car.

   To stop the car, sintered metallic brakes and special venting screens and air scoops in the backing plates for added cooling were used. All Z-11's came with T-10 4 speeds, a beefed up posi rear and a 4.11:1 gear ratio. (code JA)

  Only 57 Z-11 optioned Impala's were produced and only 7 are thought to be in existance today, making them an extremely rare and valuable piece of Chevrolet history.

  Although the Z-11 was made for racing, they weren't directly sold to race car drivers. Some ended up on car lots. And although 1963 was the only year for the Z-11, there were about 20 C.O.P.O. 1962 Impala's built mid to late in the year with aluminum front ends and equipped with 409's. These 409's had special features like the Z-11 intake manifold, special camshaft, heads, etc. There were also 18 extra sets of aluminum front ends made for that year and sold to race car drivers.

  The base price of a 1963 Impala was $2774.00. Adding the price of the R.P.O. Z-11 option of $1240.00 to that brings the total price just over $4000.00 not including destination charges, taxes, etc.

Z-11 Facts and part numbers:
  • Produced only in 1963
  • The R.P.O. Z-11 option was an additional $1240.00
  • Shipping weight-3245 lbs.
  • Curb weight-3405 lbs.
  • 57 Z-11 Impala's were produced
  • Modified 409 engine rated at 430hp@6000 RPM's. (Actual
    horsepower was 480-525)
  • Block casting #3830814. Code "QM"
  • Block part number #3838253
  • Cylinder Heads #3837731 2.19 intake/1.72 exhaust
  • Valve Covers #3837739 (left), #3837740 (right)
  • Oil pan (deep sump) #3816322
  • 2 piece Intake manifold #3830623 (top)-#3837733 (bottom)
  • Waterpump #3837691 (aluminum)
  • Cam #3837736 .556 intake/.556 exhaust lift with 325 duration
  • Crankshaft #3837472
  • Distributor #1111023
  • Coil #1115107
  • Generator #1100628
  • Starter #1107274
  • 3.65" piston stroke
  • 4.3125" bore (same as 409)
  • 13.5:1 compression ratio
  • Special cowl induction air cleaner #6418986, #3839764 (duct)
  • Tach (redlined at 6200 rpm's)
  • Borg Warner T-10 4 speed transmission (close ratio)
  • Special posi rear with 4.11:1 rear gear ratio
  • Sintered metallic brake shoes
  • Screened rear brake backing plates with air scoops
  • 15 X 5.5 wheels with 6.70 X 15 bias ply tires
  • Front coil springs #3824693
  • Rear coil springs #3824694
  • Deleted front sway bar
  • Optional sound proofing and insulation delete on most
  • Optional heater delete on most
  • Hood #3837710 (aluminum)
  • Hood catch #3837718 (aluminum)
  • Grill filler panel #3837750 (aluminum)
  • Left fender #3837765 (aluminum)
  • Right fender #3837766 (aluminum)
  • Front bumper center #3837751 (aluminum)
  • Front bumper LH #3837755 (aluminum)
  • Front bumper RH #3837756 (aluminum)
  • Rear bumper center #3837752 (aluminum)
  • Rear bumper LH #3837753 (aluminum)
  • Rear bumper RH #3837754 (aluminum)
  • Front bumper bracket LH #3837763 (aluminum)
  • Front bumper bracket RH #3837764 (aluminum)
  • Rear bumper bracket LH #3837757 (aluminum)
  • Rear bumper bracket RH #3837758 (aluminum)
  • Rear frame to bumper brace LH #3837759 (aluminum)
  • Rear frame to bumper brace RH #3837760 (aluminum)

  • Click here to test your knowledge of Z-11's in the "So you think you know Z-11's" Trivia quiz.

    All information on this page has been obtained through various books, magazines and input from visitors to this web site.