about to order parts for blown head, need help on thickness of new head gasket.

[Pantless Spency]

just getting settled in to buy the parts for my blown HG. noticed there are a variety of thicknesses in gasket for the head, from my understanding, thinner gasket = higher compression and more power? but i also want it to be a reliable car, that wont get messed up.
i am planning on having the head flattened by a machine shop.

so r3v.
what thickness should i buy, with taken into account a milled head.
so far i have seen:
Cylinder Head Gasket; 1.75mm
and
Cylinder Head Gasket; Oversize, +0.3mm; 2.05mm Thickness

[whodwho]

Unless they are taking the max slice off the head just use the 1.75 one.

[moatilliatta]

Even max slice off the head, I believe it is .030 id still run the factory thickness gasket. ;)

[jlevie]

As whodo said, what gasket to use is determined by how much material has been removed from the head. If less than 15thou I'd use the standard gasket. Otherwise the thicker one. The issue isn't a matter of compression (though it will go up slightly) or valve interference. But rather the main affect is the change in cam timing.

As an FYI: the head has cast pockets in it that are the surfacing limit.

[Pantless Spency]

cast pockets? so there will be like holes in the lining of the head if they go through it?
pretty much right now i'm planning to go with the thinner of the two.

[jlevie]

The limit pockets are depressions in the head. If you go below them there is a risk of valve and piston interference.

[Pantless Spency]

Ah i see. but that wont be likely, if done by a professional shop? and if it is ill just get a thicker gasket? or a new head... hahaha.

[Wanganstyle]

Take head to machine shop-

machine shop should NOT surface head unless needed, as these are 30 year old cars the head may already have been taken down before.

some BMW engines have 0 passes allowed on both block and head : meaning, you CANNOT take any material off head or block as it just ruins the timing set, engine is scrap if taken down.

IF its needed they will take it down, have them decide with timing in mind.

if they are a shop that builds engines they will figure it out for you; I know my engine building shop does.