Cylinder Head Identification On
                                      1977-78 GM (GMC) 5.0, 5.7 & 6.6L
                                     (305, 350 & 400 CID) Truck Engines

New lightweight cylinder heads for small block V-8 engines were released for interim 1977 & 78 production. The new heads are about six pounds lighter due to changes in internal coring of the water passages and slight modifications to the outer configuration (Fig. 1) on reverse side.

These lightweight heads were used together with current or heavy heads due to production requirements and machining capacities at the casting and manufacturing plants. Therefore, 1977 and 1978 small block V-8 engines may be assembled with either heavy or light heads, or a mixture of both.

Also, the lightweight heads consist of a 1st and 2nd design due to differences in the machining of the exhaust valve spring seats:

Lightweight Head - 1st Design

Exhaust valve spring seats are machined to 1977 or heavy head specifications (part #3911068 spring and damper assembly for intake valve and part #6263796 spring and damper assembly for exhaust valve).

Lightweight Head - 2nd Design

This head incorporates machining that allows the intake valve spring assembly (part #3911068) to be used at both intake and exhaust valve locations.

Valve Spring Identification

Part #3911068 intake spring can be identified by 1 lavender stripe approximately 2.03 free height. If the springs are identifiable by color, the cylinder heads can be identified by measuring from the top of the exhaust valve guide to the valve spring seat (exhaust spring only).

If the dimension is .75, use part #6263796 valve spring in the 1st design head.
If the dimension is .84, use part #3911068 valve spring in the 2nd design head.

                                                                             The AERA Technical Committee

Applications Of General Motors Engines

Four Cylinder:

CID		Manufacturing	Year	 Division Using		Years
Ltr		Division		Used	 Engines			Used
-----------------------------------------------------------------
86/1.4	Chevrolet		77-78	
97/1.6	Chevrolet		77-78
140/2.3	Chevrolet		77	 Oldsmobile			77
						 Pontiac			78
151		Pontiac		77-78	 Chevrolet			78
						 Oldsmobile			78


Six Cylinder:

CID		Manufacturing	Year	 Division Using		Years
Ltr		Division		Used	 Engines			Used
-----------------------------------------------------------------
196/3.2	Buick			77-78	 
200/3.3	Chevrolet		78
231 V6/3.8	Buick			77-78	 Chevrolet			78
						 Oldsmobile			77-78
						 Pontiac			77-78
231 V6/3.8	Buick			77-78
Even-Firing			

250/4.1	Chevrolet		77-78	 Chevrolet Truck		77-78
						 GMC Truck			77-78


Eight Cylinder:

CID		Manufacturing	Year	 Division Using		Years
Ltr		Division		Used	 Engines			Used
-----------------------------------------------------------------
260/4.3	Oldsmobile		77-78  
301/4.9	Pontiac		77-78	 Buick			77-78
305 V8/5.0	Chevrolet		77-78	 Buick			77-78
						 Chevrolet Truck		77-78
						 GMC Truck			77-78
						 Oldsmobile			77-78
						 Pontiac			77-78


Eight Cylinder:

CID		Manufacturing	Year	 Division Using		Years
Ltr		Division		Used	 Engines			Used
-----------------------------------------------------------------
*350H/5.7	Buick			77-78	 Oldsmobile			77-78
						 Pontiac			77
*350J/5.7	Buick			77-78	 Oldsmobile			77-78
						 Pontiac			77
*350X/5.7	Buick			77-78
*350B EFI/	Cadillac		77-78
5.7

*350L/5.7	Chevrolet		77-78	 Chevrolet Truck		77-78
						 GMC Truck			77-78
						 Oldsmobile			77-78
						 Pontiac			77-78
*350V/5.7	Chevrolet		77-78	 

*350N 
Diesel/5.7	Oldsmobile		77-78	 Cadillac			78
						 Chevrolet Truck		77-78
						 GMC Truck			77-78
*350R/5.7	Oldsmobile		77-78	 Pontiac			77-78
*350P/5.7	Pontiac		77-78
400/6.6	Pontiac		77-78	 
403/6.6	Oldsmobile		77-78	 Buick			77-78	
						 Oldsmobile			77-78
425/7.0	Cadillac		77-78
500/8.2	Cadillac		77

* To determine the correct engine refer to the 5th character of the vehicle identification number (VIN) on the left side of the dash which can be seen through the windshield.


	The AERA Technical Committee

                                      Engine Bolt Torque Information On
                             GM (Chevrolet) 1977 L-4, L-6 & V-8 Engines

Chevette L-4 Engine Torque Bolt Specifications

Usage Torques
---------------------------------------------------------------------------

Camshaft Carrier Bolts 90-95Nm 65-77 ft.lbs.
Camshaft Cover Nuts 1.4-1.8Nm 12-16 in.lbs.
Camshaft Sprocket Bolt 90-115Nm 65-85 ft.lbs.
Crankshaft Pulley Bolt 90-115Nm 65-85 ft.lbs.
Crankcase Front Cover Bolt 6-8Nm 55-75 in.lbs.
Front Cover Nut 5-8Nm 50-75 in.lbs.
Connecting Rod Nuts 46-54Nm 34-40 ft.lbs.
Coil Attaching Bolt 18-24Nm 13-18 ft.lbs.
Distributor Clamp Bolt 15-19Nm 11-14 ft.lbs.
Exhaust Manifold 26-34Nm 19-25ft.lbs.
Flywheel Bolt 54-75Nm 40-52 ft.lbs.
Fuel Pump Bolts 19-23Nm 14-17 ft.lbs.
Generator Bracket Bolt 30-40Nm 22-30 ft.lbs.
Idler Pulley Bolt 18-24Nm 13-18 ft.lbs.
Intake Manifold Bolt 18-24Nm 13-18 ft.lbs.
Main Bearing Caps 54-75Nm 40-52 ft.lbs.
Oil Drain Plug 20-27Nm 15-20 ft.lbs.
Oil Pan Bolts 5-7Nm 45-60 in.lbs.
Oil Suction Tube & Screen Ass. 26-34Nm 19-25 ft.lbs.
Oil Suction Tube Clamp 95-130Nm 70-95 in.lbs.
Oil Filter 16-23Nm 12-17 ft.lbs.
Oil Pump Cover Screws 8-11Nm 71-97 in.lbs.
Oil Pump Bolts 5-7Nm 45-60 in.lbs.
Water Pump Bolts 18-24Nm 13-18 ft.lbs.
Spark Plugs 27Nm 20 ft.lbs.


Vega - Monza L-4 Engine Bolt Torque Specifications

Size Usage Torque
----------------------------------------------------------

1/4-14 Engine Front Cover 50 in.lbs.
1/4-20 Cam Cover 80 in.lbs.
1/4-20 Oil Screen To Screen 50 in.lbs.
1/4-20 Clutch Housing Underpan 95 in.lbs.
1/4-20 Oil Screen Support To Baffle 50 in.lbs.
1/4-20 Oil Drain Back Tube To Baffle 50 in.lbs.
5/16-18 Fan Blade To Pump 20 ft.lbs.
5/16-18 Clutch Pressure Plate To Fly. 20 ft.lbs.
5/16-18 Crankshaft Damp/Pulley Sprkt. 15 ft.lbs.
5/16-18 Oil Pump To Case (Bolt) 15 ft.lbs.
5/16-18 Water Pump To Case 15 ft.lbs.
5/16-18 Oil Pan To Case 15 ft.lbs.
5/16-18 Cam Retainer 18 ft.lbs.
5/16-24 Ex. Gas Recirc. Valve To Man. 20 ft.lbs.
11/32-24 Connecting Rod Cap 35 ft.lbs.
3/8-16 Oil Pump To Case (Stud) 30 ft.lbs.
3/8-16 Distributor Clamp Nut 25 ft.lbs.
3/8-16 Water Outlet To Head 30 ft.lbs.
3/8-16 Manifold (Bolts) 30 ft.lbs.
3/8-16 Clutch Housing To Case 25 ft.lbs.
3/8-16 Clutch Pressure Plate To Fly. 30 ft.lbs.
3/8-18 Inlet Manifold To Head (Stud) 30 ft.lbs.
7/16-14 Engine Mount Stud To Block 20 ft.lbs.
7/16-14 Main Bearing Caps 65 ft.lbs.
7/16-14 Cylinder Head 60 ft.lbs.
7/16-20 Flywheel To Crank 65 ft.lbs.
1/2-13 Cam Sprocket To Cam 80 ft.lbs.
1/2-13 Damper/Pulley To Crank 80 ft.lbs.
1/2-20 Oil Pan Drain Plug 20 ft.lbs.
1.00-12 Oil Filter Connector To Case 30 ft.lbs.
1.00-12 Oil Filter Hand Tight
14mm Spark Plug 20 ft.lbs.


In-Line 4.1L (250 CID) Car - Truck Engine Bolt Torques

Size Usage Torque
----------------------------------------------------------------

1/4-20 Cam Thrust Plate 80 in.lbs.
1/4-20 Crankcase Front Cover 80 in.lbs.
1/4-20 Flywheel Housing Cover 80 in.lbs.
1/4-20 Oil Filter Bypass Valve 80 in.lbs.
1/4-20 Oil Pan To Crankcase 80 in.lbs.
1/4-20 Oil Pan To Front Cover 50 in.lbs.
1/4-20 Oil Pump Cover All 80 in.lbs.
1/4-20 Rocker Arm Cover 45 in.lbs.
11/32-24 Connecting Rod Cap 35 ft.lbs.
5/16-18 Camshaft Sprocket 20 ft.lbs.
5/16-18 Oil Pan To Crankcase 80 in.lbs.
5/16-18 Oil Pump 115 in.lbs.
5/16-18 Push Rod Cover 80 in.lbs.
5/16-18 Water Pump 15 in.lbs.
5/16-18 Rocker Cover 45 in.lbs.
3/8-16 Clutch Pressure Plate (All) 30 ft.lbs.
3/8-16 Distributor Clamp 25 ft.lbs.
3/8-16 Flywheel Housing 30 ft.lbs.
3/8-16 Manifold (Exhaust) 35 ft.lbs.
3/8-16 Manifold (Ex. To Int.)
3/8-16 Manifold (Intake) 30 ft.lbs.
3/8-16 Manifold To Head
3/8-16 Thermostat Housing 30 ft.lbs.
3/8-16 Water Outlet 30 ft.lbs.
3/8-16 Water Pump
3/8-24 Connecting Rod Cap
7/16-14 Cylinder Head 60 ft.lbs.
7/16-14 Main Bearing Cap 65 ft.lbs.
7/16-14 Oil Pump 65 ft.lbs.
7/16-14 Rocker Arm Stud 50 ft.lbs.
7/16-20 Flywheel (All) 45 ft.lbs.
7/16-20 Torsional Damper 60 ft.lbs.
1/2-13 Cylinder Head 95 ft.lbs.
1/2-13 Main Bearing Cap 110 ft.lbs.
1/2-14 Temperature Sending Unit 20 ft.lbs.
1/2-20 Torsional Damper
1/2-20 Oil Filter Hand Tight
1/2-20 Oil Pan Drain Plug 20 ft.lbs.
1/2-20 Flywheel
14mm 5/8 Spark Plug 15 ft.lbs.


In-Line 4.8L (292 CID) Passenger Car - Truck Engine Bolt Torque

Size Usage Torque
----------------------------------------------------------------

1/4-20 Cam Thrust Plate 80 in.lbs.
1/4-20 Crankcase Front Cover 80 in.lbs.
1/4-20 Flywheel Housing Cover 80 in.lbs.
1/4-20 Oil Filter Bypass Valve
1/4-20 Oil Pan To Crankcase 80 in.lbs.
1/4-20 Oil Pan To Front Cover 50 in.lbs.
1/4-20 Oil Pump Cover All 80 in.lbs.
1/4-20 Rocker Arm Cover 45 in.lbs.
11/32-24 Connecting Rod Cap
5/16-18 Camshaft Sprocket 20 ft.lbs.
5/16-18 Oil Pan To Crankcase 80 in.lbs.
5/16-18 Oil Pump 115 in.lbs.
5/16-18 Push Rod Cover 80 in.lbs.
5/16-18 Water Pump 15 in.lbs.
5/16-18 Rocker Cover 45 in.lbs.
3/8-16 Clutch Pressure Plate (All) 30 ft.lbs.
3/8-16 Distributor Clamp 25 ft.lbs.
3/8-16 Flywheel Housing 30 ft.lbs.
3/8-16 Manifold (Exhaust)
3/8-16 Manifold (Ex. To Int.) 40 ft.lbs.
3/8-16 Manifold (Intake) 30 ft.lbs.
3/8-16 Manifold To Head 40 ft.lbs.
3/8-16 Thermostat Housing 30 ft.lbs.
3/8-16 Water Outlet 30 ft.lbs.
3/8-16 Water Pump 25-30 ft.lbs.
3/8-24 Connecting Rod Cap
7/16-14 Cylinder Head
7/16-14 Main Bearing Cap 65 ft.lbs.
7/16-14 Oil Pump
7/16-14 Rocker Arm Stud
7/16-20 Flywheel (All) 45 ft.lbs.
7/16-20 Torsional Damper 60 ft.lbs.
1/2-13 Cylinder Head 95 ft.lbs.
1/2-13 Main Bearing Cap
1/2-14 Temperature Sending Unit 20 ft.lbs.
1/2-20 Torsional Damper
1/2-20 Oil Filter Hand Tight
1/2-20 Oil Pan Drain Plug 20 ft.lbs.
1/2-20 Flywheel 110 ft.lbs.
14mm 5/8 Spark Plug 15 ft.lbs.


Small V-8 5.0, 5.7 & 6.6L Passenger Car - Truck Engine Bolt Torques

Size Usage Torque
----------------------------------------------------------------

1/4-20 Cam Thrust Plate
1/4-20 Crankcase Front Cover 80 in.lbs.
1/4-20 Flywheel Housing Cover 80 in.lbs.
1/4-20 Oil Filter Bypass Valve 80 in.lbs.
1/4-20 Oil Pan To Crankcase 80 in.lbs.
1/4-20 Oil Pan To Front Cover
1/4-20 Oil Pump Cover All 80 in.lbs.
1/4-20 Rocker Arm Cover 45 in.lbs.
11/32-24 Connecting Rod Cap
5/16-18 Camshaft Sprocket 20 ft.lbs.
5/16-18 Oil Pan To Crankcase 165 in.lbs.
5/16-18 Oil Pump
5/16-18 Push Rod Cover
5/16-18 Water Pump
5/16-18 Rocker Cover
3/8-16 Clutch Pressure Plate (All) 30 ft.lbs.
3/8-16 Distributor Clamp 25 ft.lbs.
3/8-16 Flywheel Housing 30 ft.lbs.
3/8-16 Manifold (Exhaust) 20 ft.lbs.
3/8-16 Manifold (Ex. To Int.)
3/8-16 Manifold (Intake) 30 ft.lbs.
3/8-16 Manifold To Head
3/8-16 Thermostat Housing
3/8-16 Water Outlet 30 ft.lbs.
3/8-16 Water Pump 25-30 ft.lbs.
3/8-24 Connecting Rod Cap 45 ft.lbs.
7/16-14 Cylinder Head 65 ft.lbs.
7/16-14 Main Bearing Cap 60 ft.lbs.
7/16-14 Oil Pump 65 ft.lbs.
7/16-14 Rocker Arm Stud
7/16-20 Flywheel (All) 65 ft.lbs.
7/16-20 Torsional Damper 60 ft.lbs.
1/2-13 Cylinder Head
1/2-13 Main Bearing Cap
1/2-14 Temperature Sending Unit 20 ft.lbs.
1/2-20 Torsional Damper
1/2-20 Oil Filter 25 ft.lbs.
1/2-20 Oil Pan Drain Plug 20 ft.lbs.
1/2-20 Flywheel
14mm 5/8 Spark Plug 15 ft.lbs.


Mark IV V-8 Engine Bolt Torques

Size Usage Torque
----------------------------------------------------------------

1/4-20 Cam Thrust Plate
1/4-20 Crankcase Front Cover 80 in.lbs.
1/4-20 Flywheel Housing Cover 80 in.lbs.
1/4-20 Oil Filter Bypass Valve 80 in.lbs.
1/4-20 Oil Pan To Crankcase
1/4-20 Oil Pan To Front Cover 55 in.lbs.
1/4-20 Oil Pump Cover All 80 in.lbs.
1/4-20 Rocker Arm Cover 50 in.lbs.
11/32-24 Connecting Rod Cap
5/16-18 Camshaft Sprocket 20 ft.lbs.
5/16-18 Oil Pan To Crankcase 135 in.lbs.
5/16-18 Oil Pump
5/16-18 Push Rod Cover
5/16-18 Water Pump
5/16-18 Rocker Cover
3/8-16 Clutch Pressure Plate (All) 30 ft.lbs.
3/8-16 Distributor Clamp 25 ft.lbs.
3/8-16 Flywheel Housing 30 ft.lbs.
3/8-16 Manifold (Exhaust) 20 ft.lbs.
3/8-16 Manifold (Ex. To Int.)
3/8-16 Manifold (Intake) 30 ft.lbs.
3/8-16 Manifold To Head
3/8-16 Thermostat Housing
3/8-16 Water Outlet 30 ft.lbs.
3/8-16 Water Pump 25-30 ft.lbs.
3/8-24 Connecting Rod Cap 50 ft.lbs.
7/16-14 Cylinder Head 80 ft.lbs.
7/16-14 Main Bearing Cap
7/16-14 Oil Pump 65 ft.lbs.
7/16-14 Rocker Arm Stud 50 ft.lbs.
7/16-20 Flywheel (All) 65 ft.lbs.
7/16-20 Torsional Damper
1/2-13 Cylinder Head
1/2-13 Main Bearing Cap 110 ft.lbs.
1/2-14 Temperature Sending Unit 20 ft.lbs.
1/2-20 Torsional Damper 85 ft.lbs.
1/2-20 Oil Filter 25 ft.lbs.
1/2-20 Oil Pan Drain Plug 20 ft.lbs.
1/2-20 Flywheel
14mm 5/8 Spark Plug 15 ft.lbs.

                                                                       The AERA Technical Committee

                            Internally vs. Externally Balanced Flywheels On
                                                GM 2.8L Truck Engines

AERA members should be cautious when replacing flywheels on 1986 and later Chevrolet S-10 trucks and Astro Vans equipped with manual transmissions and the 2.8L engine.

Vehicles manufactured in 1986 and 1987 use the externally balanced 2.8L engine.  This engine requires a flywheel with GM Part #14088277 which carries the casting number 14033082.

Vehicles manufactured as of the 1988 model year use an internally balanced 2.8L engine.  The flywheel for this application is available under GM Part #14100556 with the casting number 14046567.

It is physically possible to mount the incorrect flywheel to the crankshaft causing a severe engine imbalance and vibration. 

                                                                             The AERA Technical Committee

                         Air Operated Tools For Valve Train Rebuilding

Air Operated Valve Spring Compressors

The use of an air operated valve spring compressor will simplify and speed up the disassembly and assembly of cylinder heads. During both operations, this tool will hold the valve spring assembly in the compressed position so that both hands of the worker are free to remove or install the valve keepers.  Buy a
heavy duty model to handle large truck and high performance cylinder heads.

Air Impact Hammer

An air impact hammer should be used to remove and install valve guides.  This tool does the job very quickly and efficiently and when used properly, does not damage the parts.  Operator fatigue is reduced by removing the old hammer approach giving a more professional aspect to the operation.


                                                                       The AERA Technical Committee