Im rebuilding a holley 650dp I think its a 4777 ,one of the accelerator pumps had this spacer in it. I am guessing it is to make it a 50cc pump. when I pulled it apart it only had a 30cc pump inside with this spacer. Anybody ever seen this before, I am not sure if I should just use this or get rid of it and put a 30cc pump in it. It says on it superspacer if that helps.

Personally I haven't seen or heard of spacers like that. The Holley versions have a special arm, pump cams and (of course) diaphram. The 50 would basically extend the squirt duration for a given squirter size. But 30cc pumps will cover most needs so I'd suggest starting with that. I believe the pink and green cams are the biggest for the 30cc.

For a 4bbl or dual tunnel ram application?

Its going on a blow thru turbo set up . I think I did figure it out though. with the spacer the 50cc pump diaphragm fits perfect. I will give it a try and if it doesn't work its not that hard to change later.