Block and Head Deck Surfacing

[zofo61]

When I get the 3500 in I am going to have balancing work done and the decks cleaned up as well as going .020 over on the bore.............what are the tolerances on the block and head deck without affecting the piston clearance.?

[bjornmk1]

it will all effect piston clearance of course.
butt in general when they machine the decks about .002" is
grinded away...so that's almost nothing.
as for the heads I would say .020" is max. if you don't want the
trouble with your intake manifold not lining up anymore.

[geoffinbc]

DO NOT grind any 660 heads or blocks if you can avoid it. They do not have the same clamping displacement on the head gaskets like a small block does. There are only 4 head bolt per bore unlike the 5 or 6 found on the smallblocks. This means you need all the head and deck thickness you can get to provide a good head gasket seal. Cleaning up is fine but if the head and deck is flat then don't touch it. Why would you bother investing money in something that is within spec anyways? If you are going to overbore the block then when you buy new pistons get one with a higher compression height if increasing compression is your goal.

[34blazer]

i usually have the heads and block skimmed to remove the rough, grainy profile from factory machining

[zofo61]

DO NOT grind any 660 heads or blocks if you can avoid it. They do not have the same clamping displacement on the head gaskets like a small block does. There are only 4 head bolt per bore unlike the 5 or 6 found on the smallblocks. This means you need all the head and deck thickness you can get to provide a good head gasket seal. Cleaning up is fine but if the head and deck is flat then don't touch it. Why would you bother investing money in something that is within spec anyways? If you are going to overbore the block then when you buy new pistons get one with a higher compression height if increasing compression is your goal.

I am decreasing compression due to boost.....I just want to clean em up not grind em down....just checking.........now............put the gun down and back away from the children

[geoffinbc]

LOL. But like I said don't even waste money if they are already straight because you wont be gaining anything. You will just be spending money which could go towards something else. Use a good straight edge and a feeler gauge and see if you can find any high or low spots. If you cant fit an .001" feeler under the straight edge then your heads a are perfect. Do the same for the deck.

Then to clean the surface you can use some sandpaper on a block and just scuff them up.

[zofo61]

THanks ....that exactly what I will do............I appreciate any and all input.....this is going to actually be fun and I want to keep it that way........