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401

General Specifications for the 1966 Buick 401 and 425 Cubic Inch Engines The following information has been directly complied from original Buick service manuals for the respective year of vehicle manufacture. These specifications should also be correct for the 1966 model year.


BOLT TORQUE SPECIFICATIONS

Use a reliable torque wrench to obtain the figures listed below. This will prevent straining or distorting the parts as well as preventing thread damage. These specifications are for clean and lightly lubricated threads only. Dry or dirty threads produce friction which prevents accurate measurement of the actual torque. It is important that these specifications be strictly observed. Overtightening can damage threads. This will prevent attainment 'of the proper torque and will require replacement of the damaged part.

Area Lb. Ft.
Spark Plugs 25-35
Crankshaft Bearing Caps to Cylinder Block 80-110
Connecting Rods 40-50
Cylinder Head to Cylinder Block 65-80
Harmonic Balancer to Crankshaft 200 Minimum
Fan Driving Pulley to Harmonic Balancer 18-25
Flywheel .to Crankshaft (Auto. & Manual) 50-65
Oil Pan to Cylinder Block 9-13
Oil Pan Drain Plug 25-35
Oil Pump Cover to Oil Pump 8-12
Oil Pick-Up Tube & Screen Housing Assembly to Oil Pump 6-9
Oil Pump to Cylinder Block 30-40
Oil Gallery Plugs 25-35
Oil Filter to Cylinder Block 10-15
Timing Chain Cover to Block 17-23
Water Pump Cover to Timing Chain Cover 6-8
Fan Driven Pulley 17-23
Thermostat Housing to Intake Manifold 17-23
Intake Manifold to Cylinder Head 25-35
Exhaust Manifold to Cylinder Head 10-15
Carburetor to Intake Manifold 10-15
Fuel Pump to Cylinder Block 25-40
Motor Mount to Cylinder Block 25-40
Fuel Pump Eccentric and Timing Chain Sprocket to Camshaft 40-55
Rocker Arm Cover to Cylinder Head 3-5
Rocker Arm Shaft Bracket to Cylinder Head 25-35
Delcotron Bracket to Cylinder Head 65-80
Delcotron Bracket Brace 18-25
Delcotron Adjustable Mounting Bracket to Cylinder Head 25-40
Delcotron Mounting Bracket Thru Delcotron to Cylinder Head at Pivot Location 35-45
Starting Motor to Block 40-55
Distributor Hold-Down Clamp 10-15
Synchromesh Lower Flywheel Housing Plate 9-13
Flywheel Housing to Cylinder Block 45-60
Fuel Filter to Cylinder Head 7-10
401

 

GENERAL SPECIFICATIONS

General
  Wildcat 445
(400 & 401 Co. In.)
Wildcat 465
(425 Cu. In.)
Code Number Prefix MR (400), MT (401) MW
Export Code Number Prefix MV Not Available
Engine Type 90° V-8 90° V-8
Bore and Stroke 4.1875 x 3.640 4.3125 x 3.640
Piston Displacement 400 & 401 Cu. In. 425 Cu. In.
Carburetor Type 4 Bbl. 4 Bbl.
Compression Ratio 10.25:1 10.25:1
Gasoline Requirements Premium Premium
Brake Horsepower @ RPM 325/4400 340/4400
Maximum Torque @ RPM 445/2800 465/2800
Taxable Horsepower 56.11 59.51
Octane Requirements - Motor 90 90
Octane Requirements - Research 99 99
Cylinder Numbers - Front to Rear - Left Bank 2-4-6-8 2-4-6-8
Cylinder Numbers - Front to Rear - Right Bank 1-3-5-7 1-3-5-7
Firing Order 1-2-7-8-4-5-6-3 1-2-7-8-4-5-6-3

 

Piston and Pin Specifications
Piston Material Cast Aluminum Alloy
Type Divorced Skirt
Finish Cam Ground
Piston Pins  
     Material Extruded SAE-1018
     Type Pressed in Rod

 

Connecting Rods
Length 6.220" (401/425)
Material Forged - SAE-1141 Steel
Rod Bearing Removable Steel Backed M/400

 

Ring Specifications
#1 Compression Cast Iron-Lubrited
#2 Compression Cast Iron-Lubrited
Oil Control Steel-Uncoated
Oil Ring Expander Steel Humped Ring
Ring Locations Above Pin

 

Crankshaft Specifications
Material SAE-1145 or SAE-1053 Steel
Bearings 5 Replaceable Steel Backed
Bearing Material #1, #2, #3, and #4 - M/400, #5 - 100A Durex
Bearing Taking End Thrust #3
Deck Height 10.00

 

Camshaft Specifications
Material Cast Alloy Iron
Bearings Steel Backed Bobbitt
Number of Bearings 5
Drive Chain
Number of Links 52
Crankshaft Sprocket Sintered Iron
Camshaft Sprocket Nylon Coated Aluminum

 

Valve Specifications
Intake Valve Material SAE 1041 Steel, 1047 or TS 8150 Steel
Exhaust Valve Material GM-N82152 (21 - 4N)
Valve Lifter Mechanism Hydraulic
Valve Spring Single Helical

 

  Lubrication System Specifications
Type of Lubrication  
     Main Bearings Pressure
     Connecting Rods Pressure
     Piston Pins Splash
     Camshaft Bearing Pressure
     Timing Chain Drip from Front Cam Bearing
     Cylinder Walls Splash & Nozzle
Oil Pump Type Gear Driven
Normal Oil Pressure 40 Ibs. @ 2400 RPM
Oil Pressure Sending Unit Electrical
Oil Intake Stationary
Oil Filter System Full Flow
Filler Type Throw-Away Element & Can
Crankcase Capacity  
     Less Filter 4 qts.
     With Filter 5 qts.



Cooling System Specifications
System Type Pressure
Radiator Cap Relief Pressure 15 psi
Thermostat Choke Type Opening at 180°
Water Pump Type Centrifugal
     GPM @ RPM 17 @ 1000
     Drive V-Belt
     Bearings Double Row
By-Pass Recirculation Type Internal
Cooling System Capacities  
With Heater 18.0 qts.
W/O Heater 17.0 qts.
With Air Conditioning 18.27 qts.
Fan Diameter and Number of Blades  
     Less AC 18" x 4
     With AC 20" x 5
Fan Drive  
     Less AC Water Pump Shaft
     With AC Thermostatic Controlled Clutch

 

Engine Dimensions and Fits
Piston Clearance Limits*
  400 &
401 Cu. In.
425 Cu. In.
Top Land .034 - .042 .034 - .042
Skirt - Top .0004 - .0010 .0004 - .0010
Skirt - Bottom .0019 - .0035 .0019 - .0035
Ring Groove
     #1 - Compression Ring .211 - .219 .209 - .217
     #2 - Compression Ring .214 - .221 .212 - .219
     #3 - Oil Ring .214 - .221 .192 - .199
Ring Width
     #1 - Compression Ring .077 - .078 .077 - .078
     #2 - Compression Ring .077 - .078 .077 - .078
     #3 - Oil Ring .181 - .187 .182 - .1885
Ring Gap
     #1 - Compression Ring .015 - .025 .015 - .025
     #2 - Compression Ring .015 - .025 .015 - .025
     #3 - Oil Ring .015 - .055 .015 - .055
Piston Pin Length 3.520 3.520
Diameter of Pin .9994 - .9997 .9994 - .9997
Clearance
     In Piston .0001 - .0004 .0001 - .0004
     In Rod .00075 .00125 Press
Direction & Amount Offset in Piston None None
*A11 Measurements in Inches Unless Otherwise Specified.

 

Connecting Rod Specifications
Bearing Length .820
Bearing Clearance (Limits) .0020 - .0023
End Play-Total for Both Rods .005 - .012
Rod Length 6.219
Rod Width .967

 

Crankshaft Specifications
End Play at Thrust Bearing .004 - .008
Main Bearing Journal Diameter 2.4985
Crankpin Journal Diameter 2.2495
Main Bearing Overall Length
     #1 .940
     #2 .940
     #3 1.127
     #4 .940
     #5 1.200
Main Bearing to Journal Clearance .000 - .0019
Bearing Journal Diameter
     #1 1.785 - 1.786
     #2 1.755 - 1.756
     #3 1.725 - 1.726
     #4 1.695 - 1.696
     #5 1.665 - 1.666

 

Valve System Specifications
Rocker Arm Ratio 1.6 to 1
Rocker Arm Clearance on Shaft .0027 - .0042
Valve Lifter Diameter .8425
Valve Lifter Clearance in Crankcase .0015 - .0030
Valve Lifter Leakdown Rate 12 to 60 Sec. in Test Fixture
Intake Valve
     Head Diameter 1.875
     Seat Angle 45°
     Stem Diameter (Top) 3.73 (Bottom) .372
     Clearance in Guide (Top) .001 - .003 (Bottom) .002 - .004
     Valve Spring (Inner)
     Valve Closed - Pounds ° Length 25.2 @ 1.690
     Valve Open - Pounds ° Length 76 @ 1.250
Valve Spring (Outer)
     Valve Closed - Pounds ° Length 46 @ 1.600
     Valve Open - Pounds ° Length 101 @ 1.160
Exhaust Valve
     Head Diameter 1.500
     Seat Angle 45°
     Stem Diameter (Top) .372 (Bottom) .3715
     Clearance in Guide (Top) .0015 - .0035 (Bottom) .0025 - .0045
Valve Spring (Inner)
     Valve Closed - Pounds ° Length 25.5 @ 1.690
     Valve Open - Pounds ° Length 76 @ 1.250
Valve Spring (Outer)
     Valve Closed - Pounds ° Length 46 @ 1.600
     Valve Open - Pounds ° Length 101 @ 1.160

 

Cubic Inches Bore Stroke Rod Length Rod/Stroke Ratio Bore/Stroke Ratio Bore Spacing
264 3.625 3.203 6.000 1.8732 1.1318 -
322 4.000 3.203 6.000 1.8732 1.2488 -
364 4.125 3.391 6.100 1.7989 1.2165 -
401 4.1875 3.640 6.220 1.7088 1.1504 -
425 4.3125 3.640 6.220 1.7088 1.1848 -


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