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  #1  
Old 07-18-2021, 08:36 PM
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Location: Tucson, AZ
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M116/117 cam lobe dimension

Would someone use a micrometer/caliper and measure a known, good camshaft lobes from the base circle to the tip of the eccentric of the lobe? This is on #08 (intake) and #09 (exhaust) cams.

I have a cam which mic's out at 1.63" on the highest/thickest lobe down to 1.62" on the lowest intake lobe.

Exhaust lobes ranged from 1.645" to 1.62".

I realize some of the difference can be attributed to operator error as, while mounted in the car, the lobes can be quite tricky to get a "straight" shot in order to get a good measurement.

Lobes show no sign of scouring.
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Last edited by Mike D; 07-20-2021 at 11:09 AM. Reason: Put in the proper measurements.
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  #2  
Old 07-24-2021, 10:21 AM
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For anyone interested, cam part #'s for the M117 5L and 4,2L engines (500SEL and 420SEL) are LH 117 051 08 01 and RH 117 051 09 01. These are denoted by the numbers stamped on the end of the camshaft, 08 and 09.

Base circle dimension 1.330" 33,782MM

Base to lobe tip 1.615" 41,021MM

This equals a lift of .285" 7,239MM

Intake and exhaust lift are the same.

Hopefully this info will help you when/if you decide whether your cam needs replacement or when sourcing a used camshaft.
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Last edited by Mike D; 07-24-2021 at 11:09 AM.
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  #3  
Old 07-24-2021, 10:42 AM
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Location: Modesto CA
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Mike,

Did you arrange for better access to measure your cams, or did you find published data?
MB shop manuals show opening and closing points @ 2mm valve lift for some of the code numbers, but not lobe lift.
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  #4  
Old 07-24-2021, 11:11 AM
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Nope, got frustrated trying to find specs so I ordered a new camshaft. Measured that one.
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  #5  
Old 07-24-2021, 03:55 PM
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A little while back in his thread about his Iron Block 560, Tony H supplied a bit of lobe lift information. One of the cams he measured was from a 117.98x, code 56/57. In. lobe lift = .284", Ex. = .276". The other was from a 116.98x, code 46/47. Lift In. = .258", Ex. = .247".

Although the valve timing for the 117 is ~5-6 degrees longer than that for the 116, the big difference is in the valve lift.
Without a significant change in valve timing, the area under the lift curve was made proportional to the displacement by increasing the lift.
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  #6  
Old 07-24-2021, 04:35 PM
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I missed those posts, probably because he was dealing with the iron block and my M117 is the alloy block. I followed his first few pages of posts but he went way off from anything I was doing at the time. Also different cam numbers.
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