O:

Your words from your last post (#15):
"4th pic is an inlet cam i bought but doesn't fit?!?"

Please define the meaning, in this context, of the word "fit".

Well it fits but when the cam lies in its place the lobes dont line up so its loose. As is my understanding. Does that make sense?

No, it does not make sense. A picture of the cam "in its place", please.

Are you referring to the cam bearings not lining up or the journal/lobes?

I have two different M110 engines in my shop.

One is a 1978 W116 280SE and the other is from a 1973 280.

There is a difference in the cam boxes.

1978 W116 280SE:



1973 W114 280:



Note the difference of the cam bearings. The '78 fuelie has 5 bearings on the intake cam and 6 on the exhaust.

The '73 (carb'ed) has 7 bearings on the intake and 8 on the exhaust.

Don't know whether it is due to model year differences or injection vs. carburetion. I suspect it is due to injection but I've been wrong before.

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So i nipped down to the garage and put that new inlet camshaft next to the old one in the housing and I can see it doesn't match, the new one only has 4 bearing journals and the old one has six to fit into the housing. Photo enclosed.

Does that make sense?

O:

Did you even trouble yourself to look at the pictures that were posted by Mike D?
They illustrate exactly your situation. Cam boxes and shafts were made with varying numbers of bearing points.

Ive been away out of the country so not everything is fresh in my mind but, yes Frank I did trouble to look at Mikes helpful post but only today was I able to go the workshop and look at the old cam and housing and start to understand it and even what journals etc are, now i understand a little more so posted what I knew. As you know I am not a mechanic or even a beginner, I was just trying to work this out. Have a nice day.

Hi Mike,

Thanks, yes at last i think i sort of understand. So my 73 280 is the same as your one with the 7 bearings on the intake. There lies my problem. I can't seem to find a replacement inlet cam with the 7 bearings to match it. I have found loads that say they fit but only have 4 journals/lobes...

The oil supply to the unused bearing points in the cam box are to be plugged from the bottom, so that the unneeded oil does not escape. The number of in-service bearing points in the cam box then matches the number of cam journals.

OK so I finally found the right camshaft in South Africa, the Old Merc Guy (https://oldmercguy.company.site) is sending today so all good, thanks for your help everyone.
I will continue to not understand these cars but will slowly learn, maybe...

Is there an antonym of Occam's Razor?

... i train and mentor people in my industry, as part of this process i tend to be patient and forgiving as new entrants learn and try to understand, I dont embarrass or shame them for rookie mistakes and little technical knowledge... its easy to bully and assert yourself online i see...

sometimes Frank thinks out loud.
And at times he spells it "b-I-e-r".

>>> I will continue to not understand these cars but will slowly learn, maybe...
we're all working on it. Some get closer than others.

Its when you catch yourself asking the same question twice that you've begun to understand things AND have a clue about what to do about it.

-CTH

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