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Old 10-13-2012, 12:00 AM   #31
taylor192
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Join Date: Feb 2012
Location: The Best Place on Earth
Posts: 1,576
My Ride: 2003.5 M3
It was a great learning experience, thanks for letting me learn on your engine!

There was definitely some lessons learned for anyone that is going to tackle this:
- we used an imperial measuring tool and converted to metric. In doing so we had a couple bad measurements or rounding errors and had to run out for shims twice. A better measuring tool would have made this much faster.
- I measured the clearances with the cam lobes pointed on an angle based on advice that the bottom half of the cam is the same diameter... yet double checking the measurements we found its best to measure with the lobes pointed straight up cause we found the measurements changed
- dropping a shim sucks on the front and back cylinders cause there's less open space to see where it went. We had one slip behind the #6 exhaust valve spring, luckily I bought a flexible magnet cause neither of us could see it.
- I was surprised by the tolerance on the shims. A 2.28 shim may actually measure as much as 2.295, which means if you're aiming for a 19 gap it becomes 17.5 and the 18 feeler gauge didn't fit. I can see why the dealerships use feeler gauges in 0.05mm increments, as the tolerance of the shims don't make it worthwhile to be super accurate.

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