E30 Zone

I want to adjust the tappets on m20/b25 engine, do I adjust them when the valves are open or closed?

Chris

valves will be fully closed, read the wiki link on M20 valve clearences really good instructions. ensure the engine is cold and repeat the process several times to get the best results.

You can make a tool for adjusting the eccentric wheel from two pop rivets and a two-three inch piece of vacuum pipe, bend one pop rivet at approx 45 degrees about 5mm from the end.

This way as you move the wheel with the tool when it tightens against the feeler gauge the vacuum pipe in the middle bends so that it does not over tighten the tappet that way you only have to repeat it twice ;)

Do them cold, and on 325i's an extra thou clearance makes them idle better. I use a 2 inch bit of coathanger wire with a short 90 degree bend on the end to move the eccentrics. Make sure the cam lobe is 180 degrees away from the rocker, and mark each adjusted rocker with a paint mark.
Also remove the spray bar and clean out the oil holes with an aerosol can of carb cleaner and a thing paper clip.