Update from a previous thread. I received a replacement 408 from blueprint to replace the one that failed . Everything was going great, no leaks, good power. i was really taking it very very easy with this motor, not going above 3,000 rpm no hard accelerations etc. Now have almost 600 miles on it. Changed the oil this past weekend using blueprint 1030 oil that they recommend. Yesterday I noticed a knocking noise on acceleration and deceleration. Today it has gotten way louder. This is the second engine from them and i am now really concerned that i either have really bad luck or that i have another motor that has failed. What could possibly be making the noise on acceleration and deceleration? Oil pressure is good. I took the valve covers off and the rockers are all god, push rods seam to be fine.