Engine noise on am stations

Are you refering to the factory installed radio? If so, they are usually very good at AM recption, however, the distance to the station will make a difference to reception quality. Let's assume the staion is within 50 miles. You should under normal circumstances have good reception. Am is noisier than FM, but AM is sensitive to electrical interference like spark plug noise and other ignition system problems. I suggest making sure the engine is tuned up by a tech. Check plug wires, plugs and other ignition system components. I have had even 1 plug out of gap tolereance give me Am noise above normal. If aftermarket radio, the manufacturers do not design a good AM section and you will get marginal reception at best.

This was common in the old days, if you realy want to listen to the am radio and you cant stand the static reving sound of your engin you may need resiter spark plugs and wires.