[nate2k5]

so i took my gsr head into the shop to get port and polished and decked and the owner told me that it looked as if it had already been milled and there was a .004 inscribed near the outside edge. he told me this was shorthand by engine shops that it had been milled 4 thousandths.

my question is, how much will this increase my compression, doesn't seem like it would affect it much, just staying on the safe side. my compression is already gonna be a bit higher than i want it with my flat face valves

 

[LSVTEC_JDMITR]

wont do much at all since its only .001" thicker than a piece of paper. I had mine done a bunch of times and had my block decked aswell to raise my compression. Make sure if you do want to go that route that you clay the motor for proper valve clearance assurance.

 

[nate2k5]

i don't plan on milling it any more. just clean it up for a good seal for the headgasket. valve clearances should be ok as is correct?

 

[LSVTEC_JDMITR]

yep should be fine as long asyou're using stock piston and rod set up

 

[nate2k5]

yah they are usdm itr pistons on gsr rods in a b18c1 block and head