280SL US emission control devices

[66andBlue]

Some previous posts have pointed to emission control devices on USA  280SL imports as one reason for its lower horsepower compared to the European 280SL models.
Aside from different injection pump models, I couldn't find a list of all the added equipment on the US models. So, I am hoping that the more knowledgable members here could provide the details.

Alfred
1966 blue 230SL automatic

[bpossel]

I am by no means an expert, but I will see if I can start a list.  Those that really know, please jump in and correct:

1.  Different distributor - changed to retard (change in timing)
2.  Speed Relay, & Speed Switch
3.  2-Way Valve added?
4.  Added fuel expansion tank in trunk (vs venting under rear of car & to outside environment, it vents back to the engine
5.  Electronic ignition added (I think this was to extend point life, vs improve exhaust emissions?)

Again, just a stab at this!  Anyone else?
Bob

bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[ja17]

Hello Bob,

The latest 280SLs had most of the emission add-ons, around 1969 sometime.  Here are my observations, they may not all be correct; all the distributors became vacuume retard versions during the later 230SLs. Actually this was not an emmission feature it just worked the opposite as did earlier versions with vacuume advance. Later US distributors dealt with emmissions by changing the advance curve. The timing relays and changeover valves Bob has mentioned are the primary ignition modifications for emmissions on USA versions. Most 280SLs had the "hot cams" same as in the Euro cars. In later years a more emmission friendly camshaft was used in the latest version USA 280SL. The injection pump on the latest USA versions were a bit tamed. The intake manifold had the vacuume dashpot to increase idle on USA cars with automatic transmissions. The "slip joint" linkage rod was also an integral part of this mechanism's function. The latest USA cylinder head "280SE/A" may have had impovements to improve combustion and emmissions.

In general the best and fanstest running 280SLs are not always the Euros. Most often the fastest 280SL is the best tuned. These fuel injected engines were a lot cleaner burning than carbureted engines of the era. The compression remained high 9.5:1 with no catalytic converter. So even the USA emission systems did not rob a lot of power.

Joe Alexander
Blacklick, Ohio