Had this issue since the moment I got the truck running with the 80e. I need two washers between the starter and the block otherwise there is an audible whirring during cranking and with engine running where the flexplate rubs on the starter snout (at least I think that's where it's rubbing) I've tried 3 different starters, same result with each. Once I shim the starter down, the noise goes away.

LM7
2004 4L85e from a 2500 Suburban 8.1L
GM 15765623 inspection cover (irrelevant)
Circle D 2B converter
Circle D flexplate

 

I have close to the same setup with the same tq converter.

I differ in that I have a TCI flexplate and have not needed shims.

Not an answer but a data point. I wish I knew more to help.

 

Yea.. it's a flexplate issue. Makes it a pita to r&r the starter. I figured buying the fancy Circle D flex would avoid this problem.

 

Id call them about it see if there may be a specific starter you need or if its a common issue with their flexplate...

 

I run a Reactor that I got from Chris at Circle D. No shims needed with my stock starter. 2006 truck.

 

.040 shim needed for mine.

 

I needed a .125" (1/8") shim. Chris said it's fine. I'm still a bit annoyed as it's more of a pita to r&r the starter as the shim can fall into the inspection cover.