i used to pack the pump housing with lubriplate or other light grease because i read thats what should be done----------then one time i thought i would give it a try without packing it anyhow----------it didn't seem to make any difference and it primed like normal with a drill------in just a few seconds-----that was over ten years ago and i have not packed a single one since-------i have done dozens of engines since and never had a single problem--------the pump seems to easily pull enough vacuum to prime with a drill-----------i could see where cranking the engine with the starter might be marginal due to the slower pump speed, and it could possibly not prime fast enough or even fail to prime at all if it were not packed with grease------i do know one hardheaded mechanic that lives in greensboro that built a turbo motor around 93/94 and he actually started the engine counting on the pump to prime--------it wasn't packed----------the engine failed to prime and it started running and had no pressure-------one of the rod bearings failed in about a minute and it started knocking------i was somewhat new to engine building at the time and i found it very interesting............RC