valve adjusting

[danval]

Hey turbo experts. what tolerances would you recommend for valve adjusting on a turbo motor. 325i head. 10psi max, daily driver and not a race car. head is being refreshed (valves re-cut to specs, head surfacing etc,) i would like to learn and read about your theories. thanks in advance

[shadowracer]

I would think there is no special "turbo" valve adjustment for an M20, at least I've never heard of such a thing, I'd just do stock lash ... maybe someone else can chime in?

There are several threads on the valve adjustment in the "M20" section though.

[TheTacoMan]

Id say normal time frame adjustments unless you are at the point where you like the rev limiter.

[digger]

clearance is more a function of cam grind profile than hp level etc. some aftermarkets cams spec a tighter clearance though

[danval]

Im really not used to this motor. In blown v8s or even turbocharged motors, you leave a "looser" tolerance on lash, that way you compensate for added heat and hence expansion. Ive never done any bmw motor, so thats why im asking for other people's experience. So, how do turbo guys set their valves then? Thank you guys!

[danval]

clearance is more a function of cam grind profile than hp level etc. some aftermarkets cams spec a tighter clearance though

Its more a heat expansion issue, lifter style, spring tension and rpm. For example, you can have the same cam profile, but if you are running solid vs hydraulic lifters, then your lash setup needs to be different. Its a combination of variables around heat expansion so you avoid valve float. Thanks again