Amdy, i think i commented very early on that id prefer a shorter stroke for road racing, i know first hand that lot of cobra guys that road race have troubles similar to yours with 4" and larger strokes where as the 3.7" motors seem to race fine. My theory is its the compression braking during decelleration a longer stroke acts like a bigger compression brake and with hot cylinders and lowering ( op is also decellerating) oil pressure it starts to make even more problems for the alreafy taxed oil sump snd system. I could be wrong.