Anybody ever polished a cast iron engine block?

[thesound]

I'm in the process of polishing a 400 Chevy small block. I don't mean that I'm doing a traditional deburring/deflashing job to prevent stress risers and cracks, but I'm actually polishing all the surfaces on the block that have the rough cast that are visible after everything's been bolted up. This job is taking FOREVER. With 80 grit greaseless, I can literally spend an hour on a spot that's about 2 square inches before the orange peel is knocked down. What I'm trying to determine is how far up in the grit range should I go with sanding before I move onto using the compounds/buffs? Same protocol as it were with polishing aluminum? (80,120,240,320,400, then emery?) Can any of you guys who have polished rough cast iron offer any tips?

P.S.-I'll be sure to post some pics when this beast is finally done

Thanks

[thesound]

NOBODY here has ever polished iron before?

[fxstcguy98]

I've never polished cast iron, but I imagine it is more like polishing steel than aluminim. I would start with an angle grinder with 80 grit flapwheels to knock the orange peel look and casting marks off the block. Then to a 120 grit flapwheel. After that start with the greaseless up to 400, then sisal/black, spiral/brown and then loose/white if you want to go that far. Hope this helps.
Darrin

i have done it .. it is not worth it to polish a block ... i had over 200 hours in mine

[thesound]

Customandsound,

How far up in the grit range did you go as far as sanding that block you polished? What I'm trying to avoid here is useless overkill. The weird thing about iron is that even with the 80 grit greaseless, the surface is left surprisingly smooth. It's almost like the compound is "wiping" the metal smooth instead of sanding it. I'm wondering if I can get away with stopping at a lower grit since the metal is getting so smooth so soon?

i started with 80 grit greasless and worked all the way to 1000 wet and dry then hit it with a sprial /white and i was done ....

the motor is in a drag car so i don't have to worry about salt and road trash hitting it