here's what I have : bare lq4 ad need to know what # grit for drum rolls to knock off sharp edges on block to prevent stress cracks,locations for knocking off sharp edges. looking down on the valley of the lifter bores there are square castings with sharp edges where the molds lined up seems to me that this area can smoothed to return oil more smoothly,also smooth water jackets. I think that anything to improve and streamline flow would be beneficial on anything oil or water flow,correct?? back to grit size #320,500, and so on. flow guys and head porters what do you suggest?? thanks ahead of time. the oldman......

 

I just used a combination of a carbide burr, hand files, and a dremel with a 80 grit sanding drum to de-burr/de-flash/smooth my LS1 block. I smoothed everything, internally and externally.

Then cleaned it thoroughly to get all the debris out.

 

thanx I was thinking around #80 to #120 grit yes and smoothing ALL orifices thanks. the oldman....

 

I would say there is no reason to use anything finer than 120. Unless your just trying to make it look Purdy. Just my 2cents.