- Run Bitcoin ABC for the first time and stop it again.
- Delete everything in directory Bitcoin\blocks.
- Copy over all the rev*.dat and blk*.dat files from bitcoin core into Bitcoin\blocks (make sure Core is not running).
- Delete all files which have a modification date after 31.07.2017. This is to make sure the chain is in pre-fork condition.
- Now run Bitcoin ABC again. It will start to reindex the blocks. This can take a long time.
- Once the blocks are re-indexed it will connect to the network and catch up with new blocks.
Also, I think it's not a good idea to have Bitcoin Core and Bitcoin ABC running at the same time on the same PC.
The bad news. The hard drive which had enough space for the chain is extremely slow. Re-indexing took me 4! days.
In the mean time I used Coinomi to sweep my forked BCH into it. Worked fast and flawless. I can recommend it.
Thanks. After moving all the dat files I had to run bitcoin-qt with -reindex otherwise I would get a "Assertion `hashPrevBlock == view.GetBestBlock()' failed. Aborted (core dumped)"