A milling question

Does anybody know a safe amount to mill off of my head? I have an 90 LS. I have heard of people milling by a thousand before, but they say it over heats sometimes.

i think most commonly people mill about 30 thousandths. Ask EDA9, i believe he had his head milled. Just make sure you take into account any future pistons and cams you may be running before you get it milled.

my head is milled 50 thou.
10.8:1 compression.

No problems.

What’s the advantage of milling the head over using a thinner head gasket? Doesn’t this accomplish the same thing? TIA


if you mill your head, make sure you have adjustable cam gears, as it will retard your cam timing a lil bit.


I do!:smiley:

how does milling your head retard your timing???

it shortens the distance between the timing gear on the crank and the ones on the cams. the belt length remains the same, so unless you shave it 1/2 belt-notch length (like 1/4"), the closest you will be able to get it will be slightly retarded. its only a few degrees depending on how much you take off, but it is significant and will affect performance.


thats why there’s a tensioner??? to take up slack…right, im sorry i dont really see how that can affect it.

tear down a motor and you will see. the tensioner is on the other side.


Originally posted by 93teggy
thats why there’s a tensioner??? to take up slack…right, im sorry i dont really see how that can affect it.

but the belt is still the same length, it still has to travel what is now a shortened distance.

hksintegra: allready done…had to replace my timing bel when it broke and i also go my head milled down to…i just dont understand how it can retard the timing i must be reallly stupid or i just cant grasp the concept…

think about it like a pully system, you have a mass with a rope tied to it. the rope is looped over a pully. let the rope be the timing belt, the mass represent the crank, and the pully represent the timing gear. if you pull on the other end of the rope you shorten the distance between the mass and pully (or crank and cam gear) which would represent shaving a head. the extra rope you pulled is taken care of by the tensioner, your right, but the gears are still set back a little. hope that helps, its kinda hard to explain with text…