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 new cams & valve adjustment
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Layne
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3 Posts

Posted - Apr 12 2008 :  08:22:18  Show Profile  Reply with Quote
I've installed "Cat" cams into my M88. They are supposed to fit all s38 and m88 variations. These are 292 deg if I recall with 10.75mm lift. The problem is that the base circle is ~1.5mm larger than the old cams. If I were to put a shim in thin enough to get the correct valve clearance the lobes would scrape on the edge of the lifter buckets. Is there a way to raise up the entire cam box? I don't see a gasket on the parts diagram, does it use one? I was thinking I could just put 2 gaskets in. I sure don't want to have to grind off all 24 buckets. Has anyone made something like this work before? Also who has a tappet depressor tool they can loan me? I can give you a deposit or something.

Thanks,
Layne

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walter
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26 Posts

Posted - Apr 20 2008 :  23:41:22  Show Profile  Reply with Quote
I read somewhere that with these camshafts you also have to make extra clearance in the cam-housing, around the bores for the lifter buckets.
I believe the cam-housing is assembled without gaskets. If you would make one, you would lose some of the extra lift and you will change the timing.
Shortening the valve stems could be a way to fix your problem. Although I have done this on many an engine, never on a high performance engine. Of course the outer tip of the stem is hardened and the result on the long run is hard to predict. It could work though, as long as the surface of the tip is concentric with the stem; donīt fool around with an angle grinder, this is work for the machine shop.
Good luck!
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Layne
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3 Posts

Posted - Apr 21 2008 :  20:13:57  Show Profile  Reply with Quote
Angle grinder, hahah. I joked about it actually, but I do know how to treat a BMW engine. As it turns out these are S38 cams, and they have a bigger base circle than M88 cams. I've (hopefully) solved the problem by sending the cams to be ground to M88 spec, rather than selling these and finding new ones. I've read that about machining the housing too, but these have plenty of room to spin around, I checked.

http://community.webshots.com/user/Layne20584
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