| The following technical bulletins were published by AERA. |
| | ENGINE BOLT TORQUE | Engine Bolt Torque Information On
GM (Chevrolet) 1977 L-4, L-6 & V-8 Engines
Chevette L-4 Engine Torque Bolt Specifications
Usage Torques
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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
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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
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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 | | CAMSHAFT TIMING CHECK | Camshaft Timing On All
Chevrolet Chevette Engines
To check the camshaft timing, the following steps should be followed:
1. Remove the timing belt front cover.
2. Rotate the crankshaft so that the timing mark on the pulley is at 0° with the #1 cylinder at T.D.C., firing.
3. Place a 1/8 drill rod, or equivalent, through the cam sprocket quick check hole (A in Fig. 1) and the hole in the timing belt upper cover.
If the holes do not line up, loosen the timing belt and rotate the camshaft until it is properly aligned.
The AERA Technical Committee | | INSTALLED VALVE TIP LENGTH SPECIFICATIONS | Installed Valve Tip Length Specification On
GM 1.6L (98 CID) Chevette Engines
General Motors explains that the installed valve tip length on
1.6L (98 CID) OHC Chevette engines is very critical to the proper
operation of this engine. Incorrect settings can result in a
noisy valve train or an engine miss.
The installed valve tip length on this engine is measured from
the rocker cover rail to the tip of the valve stem. The correct
distance should be .710 (18mm) with a .005 tolerance. If this
dimension is too long, the valve tip may be ground or a new valve
seat installed. Do not remove more than .030 (.75mm) from the
tip of the valve or interference between the valve spring
retainer and the rocker arm may occur.
It is also important to maintain .040-.050 (1.02-1.27mm) of
clearance between the rocker arm and the base circle of the
camshaft, measuring with the hydraulic lifter fully collapsed.
Correct for insufficient clearance by grinding the bottom side of
the hydraulic lifter. Alternately, too much clearance can be
reduced by adding shim stock to the bottom of the valve lifter
bore before inserting the hydraulic lifter.
The installed valve spring height of 1.300 (33.1mm), measured
from the spring seat to the top of the valve spring, must be
maintained. At this length the spring pressure should be 62-69
lbs. Adjust the closed pressure of the valve spring by adding
shims to the valve spring seat. Retest the spring pressure at
.917 (23.2mm) in length to achieve an open pressure of 170-179
lbs.
Do not pump up the hydraulic lifter with oil before installing it
in the cylinder head. This can cause the valve to stay open for
some time after initial engine start-up, leading to possible
valve, valve seat or other internal component damage.
The AERA Technical Committee
December 1987 - SPB 150
##END## | | BLOCK, CRANKSHAFT AND TIMING BELT | Data On The Chevrolet Chevette 1.6L (98 CID) Engine
TIMING BELTS
Chevrolet Chevette engines use three different timing belts:
1. Narrow 99 tooth
2. Wide 99 tooth
3. Wide 100 tooth
One solution is to build short blocks without crank gears which
would avoid the problem. On complete engines it has been found
the 99 tooth wide belt on the 1976 through 1978 models and the
100 tooth wide belt on the 1979 and up models works best because
the late block is about 1/4 higher.
CYLINDER BLOCKS
There are two cylinder blocks:
1. 1976 through 1978
2. 1979 and up (This is the high deck block with the 1/4
difference)
CAUTION: These blocks should not be interchanged.
CRANKSHAFTS
There are two crankshafts:
1. Forging No. 7184 or 7184N for 1976-79, the early crankshaft
which has smaller counterweights & the large hole (1.089) for
the converter.
2. Forging No. 1140 or 1140N, for 1980 and up, can have either
the 1.089 hole or the small hole (.825) for the converter.
CAUTION: Do not interchange crankshafts. If a late crankshaft
is used in an early engine, the larger counterweights will hit
the pistons.
The AERA Technical Committee
April 1984 - TB 314
##END## | | EXCESSIVE OIL CONSUMPTION | High Oil Consumption On 1979-85
Chevrolet Chevette 98 CID (1.6L) Engines
AERA members have reported cases of extremely high oil consumption problems with Chevrolet 98 CID (1.6L) Chevette engines. Consumption as high as 1 quart of oil every 30 miles has occurred. A thorough check of all clearances and parts (bearings, rings, guides, seals, gaskets, etc.) usually reveals no obvious cause.
General Motors engineers advise that this condition may be caused by oil pullover from the PVC system. Due to a carburetor change in 1979, GM also changed the position of the PCV valve more susceptible to sucking oil into the PCV system.
Correction of this condition can be accomplished by sealing the gaps between the camshaft cover and the PCV baffle (see Figure 1). The baffle is sealed along the top, bottom, and sides only. The corners are to be left open.
The camshaft cover should be thoroughly cleaned and dried before applying GM red RTV sealer #1052366 or use an aftermarket equivalent. Be sure to use an RTV sealer that is compatible with GM electronic engine controls.
AERA members utilizing this repair have reported total success in solving these cases of excessive oil consumption.
The AERA Technical Committee
September 1986 - SPB 136
##END## |
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