I have a knock sound in my engine that seems to only be there at idle. Not shure if it is lifters or maybe a wrist pin. Sound goes away as soon as I rev the engine some. It also only seems to be there on and off, I meen sometimes when I start the car it is there and sometimes it is not. I have got a set of new 20+pistons and rings with reconditioned rods just waiting to be used. I have another car in the garge that I am just starting on so I will not have my bay free for awhile. Do you think it is ok to run my car with this knock at times?