hello friends!

i have a 1973 280SEL 4.5 (m117.984). It needs new camshafts; i need to know, with a minimal of irrelevant tangents, what camshafts from other merc v8s i can swap in. for example, can i swap in camshafts from a 1990 560? disregarding the fact that camshaft towers SHOULD be used in conjunction with the corresponding cams, are the cam bearing/journals the same diameters? I ask because i observe the towers are different in design. so perhaps i could just swap the cams themselves and hope all i have to deal with is minute undersize.

if they do swap in, will engine performance be ridiculously altered? will "fine tuning" be neccesary?

if not, i suppose i could have the cams repaired. what is the common cost? a viable/reliable method?

Simple answer: No, 560 cams won't work.

You can use any mechanical adjustment cams on your engine. I am unsure if the "Old" 4.5 heads you have will work with hydraulic ball studs, so that will limit you to mechanical cams from any 3.5 or 4.5. Be aware there are a few different series, but 47/48 (or 46/47, my memory may be off) from a 3.5 and 52/53 from a 4.5 are identically profiled, and the best suited for a 4.5. There are others from "Smog" engines, I don't recall the numbers offhand. I (and other members) have posted the cam spec sheet before, if you do a search on these forums.

You can put in heads from any 3.5 or 4.5 engine with D-Jet and hydraulic ball studs (IIRC, that's a 74 or 75 450SE, 450SEL, or 450SL; or Euro-market 350SE, 350SEL, 350SL). You could also use K-Jet heads up to 79/80 but you may need to drill injector mount holes for the studs. Then you can use 560 cams, or any hydraulic profile cams from a 3.8 m116 all the way to the 5.6 m117.

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

so, in a consolidated sense, only 3.5 or similiar engines/models. Otherwise the camshafts from a "potential" donor would have to include the cylinder head dynamics as a definitive. am i correct here?

one aspect to expand upon is the original question regarding the bearing/journal diameter. are they the same? you state 'no, a 5.6 engine camshaft will not work', but do not explain why.

does the 560 camshaft physically fit into the 4.5 m117 camshaft tower journals?

The 560 cam MIGHT fit into 4.5 towers but you should use the corresponding cam's towers. I know a 560 cam with towers will fit into a 4.5. That's not the issue. The issue is the models post 76 have hydraulic ball studs, previous are mechanical adjust studs. I BELIEVE (Though someone can correct me if I am wrong, and please do) that the earlier heads you have do NOT have the hydraulic oiling system, so it isn't as simple as swapping the cams, towers, and studs (and rockers, since you should use the donor cam's rockers or brand new ones).

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

The shortest answer to the above highlight is: cams from iron block M117s prior to ~1976. At some point in 1975-76 a switch from mechanically adjusted clearance to hydraulic compensation of zero clearance occurred. As noted in other posts above, it is possible to change your engine to hydraulic compensation, however, the cam towers from the aluminum block engines will not bolt to iron block heads. The angle of one bolt in each tower was changed.

As to "tuning", the D-jetronic system is quite sensitive to valve overlap, and to intake duration. The hydraulic comp cams were all used with K-jetronic systems and are enough different in valve events to be disturbing to the D-jet system.

in regards to the fuel management, the effect of the alternate camshaft would be a lopey idle? or a complete convolution of the combustion event and compression efficiency, decreasing power output and lowering the already poor fuel economy?

in other words will the alternate camshaft cause the engine to barely operate or just operate differently and slightly "sloppy"? also, the d-jettronic can not be "tuned" to smooth out as much as possible?

AV:

The letter "D" in D-jet indicates Druck>Pressure; the main load sensing parameter is manifold absolute pressure (MAP). The D-jet ECU is an analog device, and its calibration is fixed, and engine specific. Since valve timing affects MAP, the choice of cams will alter the MAP characteristics. A change in MAP signal to the ECU will be interpreted as a change in throttle position or engine load, and the mixture supplied will also change. Depending on the direction of the change in MAP the resulting mixture could be over rich, or too lean.
Will engine operation be grossly changed? No. But drivability will be degraded.

Think about modern EFI systems: They are "Closed loop" meaning the computer constantly adjusts mixture for the engine based on sensors from the exhaust telling it if it's rich or lean. They also have multi-dimensional fuel mapping based on engine RPM, manifold pressure, O2 feedback, throttle position, etc. (Some engines also factor in knock sensors, fuel type IE 85% Ethanol, and more).

DJet fuel mapping is based on throttle position and manifold pressure. The DJet computer doesn't even use engine RPM to change fuel maps (One can argue it does simply because the trigger points give it a reading of RPM but the RPM has no factor otherwise really). Changing ANYTHING that will have an effect on engine manifold pressure will cause the DJet mapping to be off. If you put in cams that open the intake valves earlier and close them later, manifold pressure will be less (more vacuum) and thus the engine will run leaner, counter-intuitively (because you know it's sucking in more air, it needs more fuel, but the ECU doesn't know it's sucking in more air, only that manifold pressure is lower).

You can use a modern injection system like a Haltech to do SUPER ADVANCED tuning on one of these engines, but I have to wonder how much gains you'd get from an iron block N/A 4.5. If you just want a proper running engine, get the 46/47 or 52/53 series cams from a 3.5 or 4.5 and be done with it.

Frank, I know someone who put 3.5 cams into a 5.0 engine. I ASSUME they (he & his mechanic) used the 3.5 towers, but I may be mistaken. I know the angle changed, but either the towers already can handle the clearance difference, or they were redrilled for it. I haven't spoken with that person in a decade at least though, so I am not able to get more info.

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

and to end: the original 4.5 camshaft gears will also mate to the 560 camshafts?

To keep things necessarily simplistic: yes

so, the camshafts are:

46/47, 52/53, 54/55, 57/58...how are these identified? marks at the rear of the cmashaft?

http://www.peachparts.com/shopforum/vintage-mercedes/86694-these-cam-codes.html

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k