Tomguy,
When I go down to my hobby shop today, I'll check my 1973 MB Technical Data Manual and check the compression. I believe it is somewhere around 7 or 8. You may have a 3.5 engine in there which is high compression and was only sold for the year of 1971 in the U.S. Lean over the left front fender with the hood up of course and with a flashlight read the engine # off the bell housing below the left bank. If the # starts with 116, you have a 3.5. The year 72 was the first year for low compression for MB. Many people believe that a 72 350SL is 3.5 liter, but it isn't. It has a 4.5 liter engine in it. If you have 71 250 coupe, you have a high compression M130 engine. If you have a 72 250 coupe, you have a low compression M130 engine. I also need to point out that these are American low compression engines not to be confused with the extremely low compression engines produced for countries with very poor fuel.

Peter

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