I just picked up an 83 F-100 with the 300 I-6. The truck will not idle unless I keep my foot on the gas. (I tried turning the idle up on the carb but as soon as I kick it down the truck shuts off. The engine is also tapping quite a bit.

The valve cover was very loose so I tightened it down and it is about 1 quart low on oil. The spark plugs looked good. I'm sorry but I am familiar with Chevy engines and these Fords are new to me. Thanks in advance for any help you can offer.

 

The tapping noise would suggest to me either it needs a valve job or it has a loose rocker arm(s). Especially since the valve cover was already loose someone might have already tried finding if a rocker arm was loose, they should be tight enough so that there is no up or down movement in the pushrods but you should be able to twist them, overtightening will bend a pushrod.

 

Could the valves be adjusted wrong and be hanging open? Could that be why it won't idle?

 

The valves should be self-adjusting but they could be sticking.