Mine is a3.5 inch pin
The length of the pin out marked on the box is NOT the same as the distance of the pin from your PAP. Those are two different things, the number on the box doesn't dictate the reaction you're going to get. The distance of the pin from your axis in relation to how it's drilled is what determines ball reaction.
Also, if you want to use a ball on heavy oil, why are you taking the surface UP and then POLISHING it? Do you really expect the ball to handle heavy volumes with a shine on it? That's like putting racing tires on a minivan. The more oil you want the ball to handle, the lower the surface needs to be. You should have taken the surface down, i.e. sanded the ball, not polished it. Further, you need to ask your driller what your PAP is and how far the pin is from said PAP. It's possible the ball was drilled too weak to handle heavy oil.
I had a ball that was supposed to handle the flood, and it never handled anything over medium. Tried every surface known to man at the time, added and moved axis holes, different lines, dozens of houses. It just never handled anything more than medium. The only thing I never did was a plug and redrill, which I probably should have. Unfortunately some scumbag stole that ball, so I can't play around with it anymore