I am probably telling you something you have found out already, but my wife is sick and I had to crank over the engine to check compression: I stuck a banana plug, which is 4 mm in diameter (from Radio Shack) into pin no. 86 of the receptacle which plugs into the relay for Starter Valve, or maybe it was the relay for Mixture Control. It doesn’t matter, both relays have a 4-terminal plug, both relays are mounted forward of the brake booster, and both relays have an 86 pin. The number 86 is embossed on the underside of the relay. I just took the relay off by removing two 3mm screws, turned it over and pulled the plug off. I brushed the dust away and found pin 86. It is the lower left one in the female plug. I marked it with white paint for the next time. I had a wire connected to the banana plug and just touched it to the positive battery terminal. Ignition was off. That energizes the starter solenoid. I could stick the compression tester into the spark plug hole with one hand and touch the wire to the battery with the other. Very convenient: Everything is right there at belly button level.
1969 280SL,Signal Red, A/T, P/S, A/C, Both tops. Ret. engr. 1967 230SL - Sold
