- Feb 1, 2007
- Reaction score
1969 dated 340 fresh rebuild. 508 lift 292 duration purple shaft cam with matching lifters. P3412068 dual valve springs good to 620 lift. removed inner springs and started motor to break in cam. (oil with break-in additive used) immediately brought RPM up to 3000 and varied down to 2000 RPM and back up slowly for 30 minutes. did a little carb tuning and set idle. installed inner springs. engine sounds like I have solid lifters. put almost 200 miles on it and no change ( not getting any worse) fished out the lifters (one at a time) during spring change and all had faint circular patterns on the so no flat lobes. I've heard that some cams of other brands may do this but never heard of an MP cam doing this. kinda stumped. did the break-in right but worried about the cam going flat despite that.