There are different engine speeds for different years of the "F". Also, just because the high idle may be correct, the governor must MAINTAIN that rpm within 100 to 150 rpm of high idle. Chevy gas engines with belt driven governor can easily get out of adjustment from just tightening a worn out belt too much. Also walkers should be within 2 inches of clear forward in my neighborhood, not clear back. No cob shield for the raddle either. Walkers should have risers (fishbacks) on them for corn, if not you'll have plugging. Even under the most perfect conditions, you'll still need to clean them occasionaly.