there are rumors of the non-obd 90-91 b18a of having a maximum of 18 degrees BTDC despite how far you push the distributor. dont know if this is a physical limitation or not but it would give lots peace of mind if someone would explain in detail exactly why or why not this is possible.

before teh shop replaced my current distributor (had to let them, it was under warranty), i had much more room left after advancing to 18. ive checked and rechecked and everything lines up and checks out. no skipped teeth or anything. i cant explain the difference.