I'm working on the Merc with a 312 and 3 speed automatic (P R N D L). The owner says he can outrun this car for the first 100 yds. We checked the timing, 6 BTDC. We checked the compression. Ranged from 125 to 150 about a 50/50 split, so not at the best. He uses leaded gas, not sure about the octane. We adjusted the single 4 bbl carb. This engine fires right up, runs smoothly, sounds great. Shift into gear and the torque converter engages solidly (bumps the car forward if the rpms are a little high). This car is stock, other than the air filter. The owner recalls from youth that these cars had more guts that what he's seeing.

So any suggestions on boosting power? 

He also mentioned that he only feels the car shift once. I know it's a 3 speed, but why only one shift (not sure this is related to the lack of power). Starting in 2nd? Not sure that's possible. Any linkages adjustments that might be off? Thanks.

OK, I take it back, not stock, not a teapot carb. So that explains why there's a plugged vacuum line laying on the manifold near the distributor. The distributor is probably not original either. The vacuum connection on the distributor diaphram is of the push on rubber hose variety. Thanks for the links.

The wipers on this car are real slow, we measured 18hg on the line destined for the wiper motor and blocked off any side lines in case of leaks. Any idea what the proper amount of vacuum should be?

The wiper Motor may be slow because it needs looking into. There is a diaphragm inside which can dry out. You may be able to get a little Transmission fluid into it through Vacuum Line for Lubrication. 18hg of vacuum is more than Sufficient for Operation. If You take Distributor Cap off are Springs Visible on top of Breaker Plate? Starting to sound like a mismatched Carb and Distributor Problem.