Coal blocks do not appear to be a valid fuel source for GT bronze age machines. Is this on purpose or a feature that will come at a later date? If it's on purpose, would Greg consider changing this as the block is a vanilla fuel source. I could see if I was asking for him to make coal coke blocks compatible. That would be crazy talk.
It was made on purpose. Greg won't consider changing this, it was brought up here couple of times already.