Using an OCR (Dwell Meter)

1. Connect either the BOSCH KDJE 7457 tester or equivalent to test wire no. 153 to read the OCR (Open Cycle Ratio).
2. Read the OCR value on the meter. The reading should be equal to 60% - 70%. For dwell meter conversion use the following formula: dwell meter reading multiplied by 100 divided by degree scale of dwell meter. (for a 90° scale, use 90; for a 60° scale use 60).
3. If the OCR reading is not to specifications, adjust as follows:

Fig. 8 Engine Compartment View (Throttle Housing Area):

4. Remove the connecting boot between the metering distributor and the throttle flap housing (1) Fig. 8.
5. Remove the fuel injection cut-out on deceleration hose (2) Fig. 8.

Fig. 9 Mixture Control Regulator:

6. Remove the fuel delivery and return hoses to the fuel tank (3) Fig. 9.
7. Remove the fuel delivery and return hoses to the control pressure regulator (4) Fig. 9.
8. Remove the fuel metering distributor (5) Fig. 9 (4 screws).

Fig. 10 Do Not Tamper Plug Removal:

9. Remove the anti-stall stop (6) Fig. 10.
10. Drive the do not tamper plug (7) Fig. 10 out of the housing.
11. Reinstall the components previously removed.
12. Adjust idle speed to 900 RPM.
13. Adjust the idle mixture adjustment screw to obtain a 65% OCR reading. Recheck the idle speed, adjusting it if necessary.

NOTE: Before each reading remove the adjusting tool from the adjusting screw.

14. Install a new do not tamper plug.