R107 350SL Engine Options

[JackFitz]

Hi!

I'm currently in the process of restoring a 1975 R107 350SL. I've ran into some issues with the engine however.

During storage, unfortunately one of my pistons was damaged and needs to be replaced. I have spoken to the SL shop and they have told me that no original or aftermarket pistons are available for my engine. I've tried to track down a 92mm used piston to replace it but they all seem to have different shaped valve cutouts to mine.

I've now got the option to engine swap a complete 450SLC engine and gearbox. As I understand, the 350 and 450 blocks are both M116 engines? (I could be wrong) Would this engine from the SLC fit directly into my SL or are there differences in mounting positions?

My next concern is the ECU. The ECU and wiring loom from my 350SL is in good condition, would this work with the 450 engine or will I need the ECU and wiring loom from the 450?

Are there any other differences that I should be aware of?

Many thanks,
Jack

 

[RaceDiagnostics]

What year is your car and the done engine?

 

[alabbasi]

So your 75 350SL is a d-jetronic engine and would have mechanical lifters. The 450SLC will also need to be 75 and earlier to work with everything else as the 76 engine used CIS fuel injection, had hydraulic lifters, different cams , different intake etc. From a wiring perspective, everything will work. The 450SL and 350SL used different ECU's, fuel injectors and fuel pumps. But the engine should run with 350SL fuel pump and ECU.

The 450SL engine is actually an M117 and will be a little wide as it's a stroked out version of the same engine.

Good luck.

 

[Dickster]

Perhaps you could have pistons made?

Custom Made JE Forged Pistons | cambridge motorsports

www.cambridgemotorsport.com

 

[tonysmb]

The OP's thread is over one year old.

 

[Dickster]

Well spotted!