hey everyone, i have a 292-6 w/ a 1 barrel carb. when i start it up or put in park after driving it likes to rev high. i have only seen one adjustment screw on the front of carb. if i turn it all the way clockwise it starts to run rough and two turns cc it runs alright but still revs high. is it poss. these engines are high revvers? i don't know how many of you are exp. w this carb or engine, but any help or info would be appreciated. thanks