Bottom bracket spacer - is there such a thing?

if BB is perfectly centered as is and bolts are catching - if you spce it you'll be putting in some asymetry whcih probably wont matter -

have you correct single speed bolts?

is it that the bolts (male) are coming through the nuts(feamle)too far or is it the nuts themselves that's hitting the frame? if former - very easily fixed - later is more problematic

you file bolts

• is there counter sinking on the ring you've not used by mounting ring backwards ?
  
  
  

if bolts (the actual bolts, not the nut part) are comming out too far you can shim the outside the bolts to bring them outboard a little (i.e. put washers around bolts on the outboard side ) like this - note washers on the bolts to make double ring bolts fit single ring : http://static.lfgss.com/attachments/12505d1247947095-sl373577.jpg

can you mount the ring on the outside of the spider and space the cog at rear a little outwards?

• or even put the spider bolts in reversed (they maybe be slimmer on the bolt side than the nut side )- so that the hex sides are in board?
  
  

or if its a JIS BB you could use an ISO crank on there - it will sit 2 or 4mm out board more (older european cranksets are all ISO)

longer BB?