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1982 380SL / 1991 420SE / 1978 VW Westfalia Camper Bus.
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388 Posts
Discussion Starter #1
I just bought a 72 running 350SL with a broken head bolt so it smokes like a locomotive. I found a donor car, a 74 450SLC with a running engine of a 120K miles. I had the 450 motor out and found some differences in the intake manifold due to the smog pump set up and few other things. The main concern I have is the engine oil cooler that is on the 72 350SL that is not on the 74 450SL. Can the swap be done? What else will I expect to change out. I don't want to start pulling out the smoking but running 350SL if the swap is not possible. Please help.
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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32,472 Posts
Is the '72 a US model with the 4.5 M117?
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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32,472 Posts
Both are 117.982 so it should work. I don't know for sure but you will probably find plugs in the '74 where the oil cooler attaches. If you want to stay '72 stock looking you can change out the intake if different. I think you will need to use your '72 distributor. The 74 may have had the two vacuum lines. If there is no place to attach the oil cooler use the '74 radiator.
 

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Registered
1982 380SL / 1991 420SE / 1978 VW Westfalia Camper Bus.
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388 Posts
Discussion Starter #6
I F' up really good on the engines. As it turned out that the 74 is really a 75. It was manufactured in 11/74. I didn't know that the catalytic converter under each of the exhaust manifold made the car a 75 so I took off the intake manifold on both engines to swap only to find that they are totally different. The 75 450 engine has an extra channel right under the intake ports running the length on each side of the head. To top them off, during removal of the intake manifolds on both engine, there were two bolts on each engine broke off leaving just the stem. I had to drilled out the 75 manifold to free it and was able to save the 72's manifold; of course, that is the one I can't use and don't need. Now I have both engine with no intake manifolds.
I searched the local junk yard's website and found a 76 450SEL, a W116 car. If I pull that intake manifold and set it into the 75. Will I be able to get the engine to work with my 72 350SL? Provided that I plugged up all the extra vacuum ports for the smog control device.
 
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