Cleaned head bolt holes today. I'm not sure how many other people do this but here's my preferred method.
Before, only removed alignment dowel.
You must be registered for see images attach
After thread chaser. Doesn't do much for cleaning. Not talking repair.
You must be registered for see images attach
After stainless bore brush. Used two sizes, one for the dowel bore and one on all head bolt hole threads.
You must be registered for see images attach
I fill each bolt hole with brake clean and let sit for a few minutes and with my driver on reverse I press the bore brush down the bore and let the brush push it's self up. If you put your driver or drill on forward it will bottom out the brush and destroy it if it's to big for the bore. Just 3-4 passes each bolt hole removes most rust and oil. Blew the bolt holes out when done. Don't even bother with taps or thread chasers in the head bolt holes any more. It's rare to need to on head bolt holes after cleaning them. You will have to use your own judgement if it needs a tap or thread chaser afterwards. Every thing else I do use a thread chaser though.
You must be registered for see images attach
Box of brushes from Cornwell was $12, obviously they can be found cheaper. These just fit my driver, the box has sizes to fit Detroit DD head bolt holes and the 6.9 block.
You must be registered for see images attach