Posted by ChrisCase [76.212.213.231] on Saturday, July 30, 2011 at 09:03:28 :
In Reply to: Break-In Oil posted by dave horvath [24.131.120.209] on Saturday, July 30, 2011 at 07:46:02 :
We've had the discussion here before.
The concern with zinc is that the flat tappet cams of whence they speak are in high performance engines, with comparatively HUGE cam load compared to our flat heads.
Compare our valve train with 35 pounds of seat pressure and direct acting valve trains to a race engine with 110 pounds of valve spring pressure and a 1.9: 1 rocker ratio. That equates to six times the load on the cam/tappet interface. 35 vs 200.
These are ultra-low-performance engines, no special oils needed. Though they are not harmful either- except possibly to you wllaet thickness? Same 6x ratio perhaps? :^)