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1966 Skylark GS Nialhead Convertible Original Motor?


Craig Janakos

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I recently acquired a 1966 Skylark convertible. 401 dual quad 4 speed. According to the block and intake manifold numbers it appears to be an authentic 401 Dual Quad but I am not sure if Buick put these motors in Skylarks? Block also has "M 80" and "GM 705". Is there a way to confirm original motor to this Skylark or a motor swap? VIN verifies V8 GS. Thanks!

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Buick Skylark GS Convertible Super Turbine (aut. 2) , model year 1966, version for North America U.S. (up to September)

1966 Buick Skylark GS Convertible Super Turbine (aut. 2) specs

Performance option below, my guess it's NOT a 2X4 carbureted engine.

 

 

Buick Skylark GS Convertible Power Pack Super Turbine (aut. 2) , model year 1966, version for North America U.S. (up to September)

1966 Buick Skylark GS Convertible Power Pack Super Turbine (aut. 2) specs

owertrain

 

Engine manufacturer:

GM Buick Nailhead V-8 401 (Wildcat)

Engine type:

spark-ignition 4-stroke

Fuel type:

gasoline (petrol)

Fuel system:

carburetor

Charge system:

naturally aspirated

Valves per cylinder:

2

Valves timing:

 

Additional features:

 

 

 

 

 

Emission control:

 

Emission standard:

 

 

 

 

 

Cylinders alignment:

V 8

Displacement:

6572 cm3 / 401 cui

Bore:

106.36 mm / 4.1875 in

Stroke:

92.46 mm / 3.64 in

Compression ratio:

10.25 : 1

Horsepower net:

 

 

 

Torque net:

 

 

 

Horsepower gross:

253.5 kW / 345 PS / 340 hp (SAE gross)

 

/ 4600

Torque gross:

603 Nm / 445 ft-lb

 

/ 3200

Redline rpm:

 

 

 

Car power to weight ratio net:

113 watt/kg / 51 watt/lb (estimated by a-c)

Car power to weight ratio gross:

151 watt/kg / 68 watt/lb

Car weight to power ratio net:

8.8 kg/kW / 6.5 kg/PS / 14.5 lbs/hp (estimated by a-c)

Car weight to power ratio gross:

6.6 kg/kW / 4.9 kg/PS / 10.9 lbs/hp

 

 

Fuel capacity:

76 liter / 20.1 U.S. gal / 16.7 imp. gal

Engine lubricant oil capacity:

3.8 liter / 4 U.S. qt / 3.3 imp. qt

 

plus 0.9 liter / 1 qt for filter change

Engine coolant capacity:

17.5 liter / 18.5 U.S. qt / 15.4 imp. qt

Battery capacity (Ah):

70

 

 

 

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The reason I say the above doesn't have 2X4 is if you look at the full size Wildcat option G/S below where it actually says 2X4's and the HP is 360 instead of 340 and a 400" ,   the engine below is a 425 nailhead and is only used on the big cars.

 

Buick Wildcat GS Sport Coupe Power Pack (aut. 3 speed)
as offered for the year 1966 since October 1965 in North America U.S.

How many were produced ? Check Buick Full-Size 6gen available production numbers data.

Production/sales period of cars with this particular specs:

October 1965 - September 1966

Modelyears:

1966

 

 

Country of origin:

USA United States

 

 

 

/FLAG/USA.jpg

Make:

Buick

Model:

Full-Size 6th generation (Electra, Le Sabre, Wildcat)

 

1965-1970

Submodel:

Wildcat 2-Door Hardtop

 

1965-1970

Optional equipment:

 

EEC segmentation:

F (luxury cars)

Subsegment:

S-C-L (luxury coupes)

Class:

full-size luxury / luxury car

Body style:

hatchback coupe

Doors:

2

Traction:

RWD (rear-wheel drive)

 

 

 

Engine specifications

 

Engine manufacturer:

GM Buick Nailhead V-8 425

Engine type:

spark-ignition 4-stroke

Fuel type:

gasoline (petrol)

Fuel system:

2 carburetors

Charge system:

naturally aspirated

Valves per cylinder:

2

Valves timing:

 

Additional features:

4-barrel

 

 

 

 

Emission control:

 

Emission standard:

 

Cylinders alignment:

V 8

Displacement:

6970 cm3 / 425.3 cui

What power?

 

Horsepower net:

 

 

 

Torque net:

 

 

 

Horsepower gross:

268.5 kW / 365 PS / 360 hp (SAE gross)

 

/ 4400

Torque gross:

631 Nm / 465 ft-lb

 

/ 2800

 

 

Car power to weight ratio net:

103 watt/kg / 47 watt/lb (estimated by a-c)

Car power to weight ratio gross:

138 watt/kg / 62 watt/lb

Car weight to power ratio net:

9.7 kg/kW / 7.1 kg/PS / 15.9 lbs/hp (estimated by a-c)

Car weight to power ratio gross:

7.3 kg/kW / 5.3 kg/PS / 11.9 lbs/hp

 

 

Full engine data: horsepower/torque rpm, etc. - click the button below:

Edited by Pfeil (see edit history)
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The only Buick engine I’m aware of from the 60’s that had 2 4’s was the Riviera engines and I think that engine was optional. Don’t have my “Standard Catalog of American Cars” with me, so I’m just guessing more or less. The 401 with the 2 4’s would make it a go fast machine.

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17 hours ago, George Smolinski said:

The only Buick engine I’m aware of from the 60’s that had 2 4’s was the Riviera engines and I think that engine was optional. Don’t have my “Standard Catalog of American Cars” with me, so I’m just guessing more or less. The 401 with the 2 4’s would make it a go fast machine.

Did you happen to see the specs on the Wildcat I provided. notice how many carburetors???

Buick Wildcat GS Sport Coupe Power Pack (aut. 3 speed)
as offered for the year 1966 since October 1965 in North America U.S.

How many were produced ? Check Buick Full-Size 6gen available production numbers data.

Production/sales period of cars with this particular specs:

October 1965 - September 1966

Modelyears:

1966

 

 

Country of origin:

USA United States

 

 

 

/FLAG/USA.jpg

Make:

Buick

Model:

Full-Size 6th generation (Electra, Le Sabre, Wildcat)

 

1965-1970

Submodel:

Wildcat 2-Door Hardtop

 

1965-1970

Optional equipment:

 

EEC segmentation:

F (luxury cars)

Subsegment:

S-C-L (luxury coupes)

Class:

full-size luxury / luxury car

Body style:

hatchback coupe

Doors:

2

Traction:

RWD (rear-wheel drive)

 

 

 

Engine specifications

 

Engine manufacturer:

GM Buick Nailhead V-8 425

Engine type:

spark-ignition 4-stroke

Fuel type:

gasoline (petrol)

Fuel system:

2 carburetors

Charge system:

naturally aspirated

Valves per cylinder:

2

Valves timing:

 

Additional features:

4-barrel

 

 

 

 

Emission control:

 

Emission standard:

 

Cylinders alignment:

V 8

Displacement:

6970 cm3 / 425.3 cui

What power?

 

Horsepower net:

 

 

 

Torque net:

 

 

 

Horsepower gross:

268.5 kW / 365 PS / 360 hp (SAE gross)

 

/ 4400

Torque gross:

631 Nm / 465 ft-lb

 

/ 2800

 

 

Car power to weight ratio net:

103 watt/kg / 47 watt/lb (estimated by a-c)

Car power to weight ratio gross:

138 watt/kg / 62 watt/lb

Car weight to power ratio net:

9.7 kg/kW / 7.1 kg/PS / 15.9 lbs/hp (estimated by a-c)

Car weight to power ratio gross:

7.3 kg/kW / 5.3 kg/PS / 11.9 lbs/hp

 

 

 
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I checked the block # with the VIN and it is a match. So I guess it's the original 401. I recently read that the factory sent out kits to dealerships to convert the Skylark to dual quads, but very few dealers did the conversion. Also read that Buick made 31 factory Skylark 401 2x4 near the end of production just to get them out there? I also read that there were many aftermarket conversions? Either way, the car car produces a big smile when driving. Thank you again for your replies. 

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3 hours ago, Craig Janakos said:

I checked the block # with the VIN and it is a match. So I guess it's the original 401. I recently read that the factory sent out kits to dealerships to convert the Skylark to dual quads, but very few dealers did the conversion. Also read that Buick made 31 factory Skylark 401 2x4 near the end of production just to get them out there? I also read that there were many aftermarket conversions? Either way, the car car produces a big smile when driving. Thank you again for your replies. 

It's possible, but improbable that Buick was just getting the 2X4 off the shelf because of the new edict coming down from the 14th floor of GM for the new 1967 GM cars. The edict said NO multiple carburetion for 1967. The new president of GM (ED Cole) in 1967 would be the father of the small block Chevrolet, the Corvair, the Vega who pushed the edict through.

  This new edict would exclude Cole's beloved Corvette and Corvair and would axe Pontiac's Tri-Power, Oldsmobile resurrected for 1966 J-2 from an eight-year absence from 1958.

 Buick for 67 had made redundant the Buick nail head and a 2X4 system for the new Gen 2 Buick designed big and small block engines.

 Pontiac would increase displacement on all its V-8's. The 326 would become the 354 (350 in name) the 389 would become the 400 and the 421 would become the 428 (really a rounded up 427) and redesign the cylinder heads valve angle and port angles and to increase valve diameter size. All done to promote better breathing and keeping HP up from previous engines. 

 

Thank you, Ed Cole. 

 

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