Everytime I try to install my HEI it tilts at the bottom so I can't seat it properly. I engage the cam gear every time, because the rotor turns to the # 1 cylinder like I want, but it alwaystilts,WHY?  

Make sure you have your oil pump drive slot positioned correctly so it will engage the bottom of your distributor shaft just like a flathead screwdriver in the head of a slotted screw. Other than that I don't know.  

I'm almost certain it is contacting pump rod , but it still tilts at an angle..What next?  

Has that distributor been run in that engine before? If not you might not have a dist for a chevy block. Olds maybe? Also, check for an obstruction. Dist. are machined to pretty tight tolerances so I can't imagine what could be going on.  

I found that the intake i bought off ebay was not machined correctly. I had the intake machined and the distributor dropped right in. thanks..