Introduction, Tightening cylinder head boits, Exhaust manifold nuts – Generac 86640 User Manual
Page 28: Carburetor bolts, Adjusting vaive clearance, Valve clearance hot intake s 0.010 inch (0.25mm), Checking drive beits, Measuring compression pressure
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Section 2.1- BASIC ENGINE MECHANICAL
Introduction
This section covers some of the basic engine servicing
tasks. Included In the Section are commonly used tightening
procedures for cylinder head bolts, manifold nuts and carbu
retor bolts. Also covered are valve clearance adjustment and
drive belt checking procedures.
Tightening Cylinder Head Boits
RetIghten cylinder head bolts while the engine Is cold, at
approximately 68* F. (20* C.). Tighten the bolts as follows:
1. Remove all spark plugs, oil pump drive gears, retainer and
bolts (Figure 1).
2. Tighten bolts to 47-51 foot-pounds (64-69 N-m) in the
sequence shown below.
Tighten Manifoid, Exhaust Manifoid and
Carburetor Fasteners
INTAKE MANIFOLD NUTS:
Tighten to 12-15 foot-pounds (16-21 N-m).
EXHAUST MANIFOLD NUTS:
Tighten to 12-15 foot-pounds (16-21 N-m).
CARBURETOR BOLTS:
Tighten to 4.3-5.8 foot-pounds (6-8 N-m).
Adjusting Vaive Clearance
Adjust valves while engine is warm, but not running, as
foltows:
1. Set No. 1 cylinder at top dead center (TDC) of Its compres
sion stroke. Then, adjust valve clearance 1,2,3 and 6.
2. Set No. 4 cylinder at top dead center (TDC) of its compres
sion stroke and adjust valve clearance 4, 5, 7 and 8.
3. Set valve clearance as follows:
VALVE CLEARANCE HOT
INTAKE s
0.010 Inch (0.25mm)
EXHAUST =
0.012 Inch (0.30mm)
Figure 3. Valve Clearance Adjustments
© (
2
) (?) (
6
)
(i) d) (z)
4. When valve clearances are properly set, tighten the adjust
ing screw locknut to 8-11 foot-pounds (11-15 N-m).
Checking Drive Beits
Inspect drive belts for cracks, fraying, wear, ollllness.
Replace, if necessary. The belts should not touch the bottom
of the pulley groove. To check belt tension, apply a force of
approximately 22 pounds (10 kg) midway between pulleys.
Belt deflection should be as follows:
NEW BELT a 0.59^).75
inch
(15-1
9m)
USED BELTaO.71-0.87
inch (18-22mm)
Measuring Compression Pressure
Warm up the engine. Then, shut down and remove ail spark
plugs. Use a standard automotive type compression gauge.
Hold the throttle and choke valves on carburetor wide open.
Page 2.1-1