From digest.v7.n1834 Fri Jun 5 18:22:03 1998
From: "Brett Anderson" <>
Date: Fri, 5 Jun 1998 20:06:55 -0400
Subject: Re: M30 Valve adjustment too tight? (Brett A.?) BA

>Date: Fri, 5 Jun 1998 11:17:06 -0500
>Subject: M30 Valve adjustment too tight? (Brett A.?)
>Okay, I was able to quiet the valves down by tightening up the gaps.
>Some were a little loose, but just for kicks I gapped them really tight
>and now they're at about 9 thousandths. Man, the car has excellent
>throttle response now! Only problem is that it's "camming" right now
>and has a lumpy American V8 idle that shakes the car. I took off the
>plug wire to the No. 2 cylinder and that smoothed things out. So I
>probably have some carbon in my No. 5 valves and will check it out this
>weekend. (Any ideas on why this cylinder is acting up?)
> Here's my question: I know the gaps are supposed to be between
>12 and 14 thousandths, but they were too loud at 13. I want to adjust
>them again tomorrow and was wondering if leaving them at around 10-11
>thousandths would be okay. Many of you M30 owners say you gap yours to
>10 thousandths anyway--do you guys have any problems? Brett, what do
>you think? Will my rocker arms snap at 6800 RPM (I have a Jim C chip)
>if they're this tight? Accelerated cam wear? The valves are very quiet
>with things as tight as they are now and I think if I can check the
>adjustment on the No. 5 cylinder, the whole engine should be smooth and
>quiet again. I want to make sure I'm not going to driving a
>ticking-time-bomb when I put that valvecover back on for good.
>PCA / IDSA / CIP / BMW CCA #156642 (NCC)

Adjusting the valves this tight causes misfire at idle, your HC will be through the roof, you will probably fail any emissions sniffer test the car needs to go through.
You will also run severe risk of eating the cam in a very short time. The system is designed for 12 -14 thou, it has been my experience, along with many others, that 14 thou, dead cold, is ideal. Attempting to quiet the valves is a stupid idea, if you want your engine to run as quiet as a Honda, buy a Honda. You should be able to hear every single valve, plus the clicking of the injectors. If the valves are louder than the injectors, the valves are due for adjustment. If the injectors are still louder than the valves, you are ok

Brett Anderson
BMW and ASE master technician

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