I'm not for sure but my guess would be that poly-locs and drippers won't work on the same heads. Some of the locs won't even fit under a stock valve cover period. The first set I got came with the Erson roller rockers. I had to use two rubber VC gaskets to clear the nuts. The set that I just bought are ProForm and are shorter so there was no problem but I still don't think they would clear drippers.