I just installed an olds 350 engine that had been sitting for 3 years, when I cranked it up I heard a knock, before I bought this motor it had been running smoothly on a engine hoist, the car hasn’t been drove yet just ran 2 times 30 mins long at idle...all parts & fluids are new..could this be lifters I’m hearing?...knocking or tapping has gon down since initially starting the car, can anybody offer me some help???