Re: Synching carbs and ignition on 1972 85 hp V4

[Don]

OK, well I think there is some confusion here….I read the OMC instructions Frank posted about the 5degree BTDC adjustment, but that is confusing also. This step refers to an earlier adjustment/set up, which I think is getting confused for idle speed…
The 5 degree BTDC adjustment is for the "pick up timing adjustment", which is not the same thing as setting the idle speed. There is no timing spec for idle speed on these engines, proper idle speed is controlled by screwing the idle speed control screw in/out slightly to set proper idle RPM in gear. When these engines are idling, the throttle cam should not be touching the roller.
The 5 degree BTDC pick up timing is checked when the scribed line on the throttle cam is bisecting the throttle roller, when the cam just starts to open the carb butterflies, this is an off idle speed setting. The pick up timing is adjusted by rotating the plastic yoke in/out on the threaded throttle linkage, not by turning the idle speed screw in/out.
These adjustments are not difficult but can be confusing. The sync adjustments must be performed in order, starting with checking the TDC pointer. Skipping a step, or performing steps out of order will create confusion and running issues.