m30 Valve clearances

[Ryan12345d]

Im currently in the process of doing the headgasket on my 535i and thought id adjust my valve clearances while its going back together. I have found some info (that it should have .014" clearance, but some say this is too noisy and to run .012"), but is this hot or cold, is this for inlet or exhaust?i always thought exhaust needed a larger clearance due to the extra heat and expansion of the valve.

[BigKriss]

I ran .012" cold for both inlet and exhaust valves. won't the machine shop adjust the valves for you though, when you get it back from them?

[Ross]

They are very sensitive to valve lash. Make sure the cam is deadnuts where you want it and set 'em on the loose side. You may have a little clatter but your idle will be smoother.

[Jeff N.]

Kris: You must adjust them after the head is torqued down.

.012 is fine for both sides. Set them all then go around and check them again before you call it done.

The "smooth idle" with the larger valve lash setting is because you minimize/eliminate the cam overlap. This will cost you a little power. Your choice.

[BigKriss]

Hi Jeff. When I got the head back from the shop, I checked the valve clearances after the head was torqued down and they where all at .012" also, so no before / after change.

[Jeff N.]

Right. You did the right thing though. Checked them. You can set them in advance but you need to verify them after you torque the head down.