This motor is driving me to drink! Heres the picture: 1954 Mark 20 thats been rebuilt from end to end, has all new magneto parts (except points, that are good, and a mag rotor that has been recharged). The bearings and seals are new, and it has nice compression. Yet it will NOT run on the lower cylinder. Rev it up a bunch and the lower cylinder will come in-sort of-but drop her down to idle and out it goes again. Grrr!!<br /><br />Tried a new trick last night. I clamped a spare spark plug (with a ¼ inch gap) to the block and fired the motor up. As usual she ran great on the top cylinder, but no spark was seen on the lower. Huh? thought I, for it had sparked beautifully when I wheeled her over with the plugs out. Reving the motor up, the bottom plug (the one clamped to the block) began sparking intermittently, and then really nicely. And as it did, the TOP cylinder began to miss. (I had noted this several times before, without an explanation as to why.) Letting the motor idle back down, the top came back and it idled fine, but the lower cylinders spark started going away again. What the hell!<br /><br />It seems as if one cylinders spark is FIGHTING the others, since when one has spark the other does not (as if the coils were not the same polaritywhich they are--I checked).<br /><br />Im stumped! Anyone got a suggestion of what to do next, other than bolting on a Phelon mag or setting fire to it?<br /><br />Jeff
