CARBURETED Models (Hot Engine)
- With engine at normal operating temperature, disconnect vacuum hose No. 2 from distributor vacuum advance diaphragm B. Connect vacuum gauge to hose.
- Start engine and run at idle. If there is no vacuum, proceed to step 3). If there is vacuum on gauge, replace thermovalve A and retest.
- Attach a hand vacuum pump to both vacuum advance diaphragms using a "T" fitting. Plug vacuum advance hoses. Pinch off hose to vacuum diaphragm B. Start engine and apply 16 in. Hg vacuum. Ensure timing advances and vacuum remains steady. If not, replace advance diaphragm and retest.
- If timing did not advance, check breaker plate for freedom of movement. Repair or replace as necessary. If breaker plate moves freely, replace vacuum advance and retest.
- Release pinched vacuum hose and apply 16 in. Hg vacuum. Timing should advance more than in step 3) and remain steady. If timing advances more than in step 3), system is okay. If timing does not advance more than in step 3) or will not stay advanced, replace vacuum advance and retest.