Source

I built a motor 10 years and 12,000 miles ago with many 440 Source parts. I used their 383 to 496 stroker kit, they balanced it, 440 source heads, 440 Source rocker arms, and many other 440 source parts. I did buy aftermarket machined valve locks for the heads. I beat the snot out of it for a decade. Spun it up to 6 grand daily. Had a lot of fun with it. Their customer service was excellent. Eventually, the needle bearings on the rockers let go and the metal circulating through the engine trashed the cam. I blame myself for that. I have never been known amongst my friends for keeping a good preventative maintenance schedule. In 10 years, I had only adjusted the valves in this motor (solid lifter cam) once. Maybe the presumably loose tolerances on my valve adjustments were responsible for hammering on those needle bearings. So I really can't even blame 440 Source for the eventual failure of the motor I built.
My experience with their stuff was very positive.
– Jay