Drilling steam holes in smallblock Chevy heads
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guess we're just trying to make sure don't screw up cust. brought [new] pr [aftermarket] sb heads cust. brought [old 400sb chev] head gskt . wants us to lay head gskt on blk surf. side , mark ALL steam holes , then drill ? is there ANY thing we need to sure of before we start drilling or do we just drill , then give back to cust. [we've been in the eng. rebuilding business [33+yrs] BUT , as U can tell this is the 1st time anyone has asked us to drill steam holes ???? | guess we're just trying to make sure don't screw up cust. brought [new] pr [aftermarket] sb heads cust. brought [old 400sb chev] head gskt . wants us to lay head gskt on blk surf. side , mark ALL steam holes , then drill ? is there ANY thing we need to sure of before we start drilling or do we just drill , then give back to cust. [we've been in the eng. rebuilding business [33+yrs] BUT , as U can tell this is the 1st time anyone has asked us to drill steam holes ???? | ||
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You should use a 400 head gasket as a template to mark the heads and Drill the 3 holes on the intake side using a 3/16 drill bit at a 10 degree angle towards the exhaust side of the head. Drill the 3 remaining holes using a 1/4 inch drill bit straight down towards the top of the head. | You should use a 400 head gasket as a template to mark the heads and Drill the 3 holes on the intake side using a 3/16 drill bit at a 10 degree angle towards the exhaust side of the head. Drill the 3 remaining holes using a 1/4 inch drill bit straight down towards the top of the head. | ||
1- Start by marking the approximate steam hole locations with a marker or die. Next insert 2 dowel pins into the heads dowel pin holes and lay the 400 head gasket onto the head over the dowel pins. This will keep the gasket aligned precisely as you mark the holes. | 1- Start by marking the approximate steam hole locations with a marker or die. Next insert 2 dowel pins into the heads dowel pin holes and lay the 400 head gasket onto the head over the dowel pins. This will keep the gasket aligned precisely as you mark the holes. | ||
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