High Altitude
- Warm up engine and check ignition timing at idle. Disconnect hose from distributor sub-diaphragm, and plug hose end.
- Check ignition timing. Timing should be 0° BTDC. Reconnect hose to sub-diaphragm. Verify that timing advances to about 12° BTDC.
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- Disconnect vacuum hose between check valve and vacuum pipe at vacuum pipe side. Plug pipe end. Ignition timing should remain stationary for more than one minute. Stop engine and reconnect hoses to proper locations.
- Remove 3 hoses from ports on top of HAC valve. Blow air into each hose and check that air flows into carburetor. Reconnect hoses to proper locations.