Originally Posted by Diseasel300

The 60x engines have hydraulic tappets. If the car sat for a long time, they can drain out and be noisy. Usually they'll pump back up in 10-20 miles of driving, but sometimes they don't if there's a bunch of varnish or sludge in them. They can be taken apart and cleaned (I've had good success doing this on 3 different engines) or replaced with new (parts aren't that expensive). Try a 5W-40 oil and drive it on the highway for 30+ minutes and see if it shuts them up.