Vanagon F4-1970cc 2.0L (1982)
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flash timing mark with timing light, and note indicated angle (basic angle)
Note: Start of centrifugal advance is shown by movement of notch while increasing rpm
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increase engine speed slowly to 1600 rpm
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bring notch back to original setting by turning knob on tester and read off advance value
Note: To determine centrifugal advance, subtract basic advance angle from advance angle measured
Example: last advance angle measured (-) minus basic advance angle (=) centrifugal advance
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compare centrifugal advance to specification chart
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repeat check at 3400 rpm
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when check completed, reconnect vacuum hoses
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reconnect idle stabilizer plugs
Vacuum Advance Unit, Checking For Leakage
Distributor vacuum unit, leak checking
Work sequence
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connect vacuum tester between intake manifold and retard connection on vacuum unit
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plug vacuum hose for retard connection
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set vacuum tester to allow vacuum to pass through
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start engine and run at idle
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disconnect hose from advance connection on vacuum unit
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set vacuum tester so that it holds vacuum on side connected to vacuum unit
Note: Vacuum registered on tester must not drop by more than 10% within 1 minute
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connect vacuum tester between throttle valve housing and advance connection on vacuum unit
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set vacuum tester to allow vacuum to pass through
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increase engine speed until reading on vacuum tester is higher than 240-280 mbar (180-210 mm Hg)
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if no vacuum is registered on tester, check if connection at throttle valve housing is blocked
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set vacuum tester so that it holds vacuum on side connected to vacuum unit
Note: Vacuum registered on tester must not drop by more than 10% within 1 minute
Vacuum Advance Angle, Checking
Vacuum advance angle, checking
Work sequence
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connect SIEMENS tester or equivalent (or tach and timing light) according to manufacturer's instructions
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connect vacuum tester between throttle valve housing and vacuum advance unit connection
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set vacuum tester to allow vacuum to pass through
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disconnect plugs from idle stabilizer and connect together
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start engine and adjust idle speed to 900 rpm
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if SIEMENS tester or equivalent is being used, read off indicated advance angle (basic angle)
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if using timing light, flash scale and note advance angle (basic angle)
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increase engine speed until reading on vacuum tester is higher than 240-280 mbar (180-210 mm Hg)
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switch vacuum tester so that tester holds vacuum on side connected to vacuum unit
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let engine continue to run at idle and readjust to 900 rpm if necessary
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reduce vacuum on vacuum tester to 240-280 mbar (180-210 mm Hg) or 90-160 mbar (70-120 mm Hg)
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note advance angles
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determine vacuum advance by subtracting basic advance angle from measured advance angle
Example: last advance angle measured (-) minus basic advance angle (=) vacuum advance
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compare vacuum advance angles with specified values on specification chart
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reconnect vacuum hoses and adjust idle speed
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reconnect idle stabilizer