Retraction settings for ABS

[axsdenied 0]

After recently starting printing in ABS I am trying to figure out which retraction settings to use.

ATM I am using 4.5mm-5mm @ 40mm/s. During moves (speed = 250mm/s) some plastic oozes out of the nozzle and stays on the print. Some of it later gets picked up by the nozzle and then it burns there eventually leaving black marks on the print. This is very noticeable as I am printing in white ABS.

Printing settings:

layer height 0.25, 50mm/s @ 260 degrees C

bed initially at 110 degrees C lowered gradually to 90 degrees C

fan at 10% @ about 1mm height

The high temperature is needed as the part must be very strong. Also the parts are very large utilising almost the whole build area.

Any hints what other people are using for retraction? What are the maximum safe limits of the retraction values?

Thanks in advance for any hints.