1967 model 20 hp Merc stator mystery.

[G. Philip Coci]

I have disassembled this frazzeling thing 5 times. All new parts except the points (can't buy them) but they are clean and in good shape. Ohms test of electrical continuity looks ok. I get good blue spark on one cyl and nothing on the other. I installed two new aftermarket coils. The insulation looks a little thin on the coil that is not firing. Could the coil be defective? Could the kill switch shunt wires be causing a problem? This is the same problem I had with all of the old parts. So, I am nowhere. I am fixing to try the better looking of the two old coils. How do I test before assembly?

 

[Chinewalker]

Re: 1967 model 20 hp Merc stator mystery.

Hi Goco,<br /> I would start with the points. Being that they're original issue, make sure the're SPOTLESS. Run some 320grit wet/dry sandpaper through them until both contacts shine. Then run a strip of index card dipped in laquer thinner or carb cleaner through the points to remove any grit, oil, etc. Also, make sure the armature plate itself below the points is spotless so that the points make good ground to the armature plate.<br /> If you still suspect a coil, try swapping them and see if the problem follows the coil.<br /> As for the kill switch, are you using the original screws that held the wires to the nylon terminal block? I made the mistake once of grabbing the wrong self-tapping screw ofrf the bench - turns out it was too long, went all the way through the terminal block and grounded that wire to the motor block. Had me scrathing my head for a long time on that one...<br /> Also, check the plug wires up under the armature where they route around the plate itelf - sometimes the clamps they used can result in a weakened wire or cracked sheathing....<br />- Scott

 

[G. Philip Coci]

Re: 1967 model 20 hp Merc stator mystery.

Hi Chinewalker,<br /><br />Well bud, done what you said and got positive results. Seems to be runnig like new. Many thanks. Do you know about oil mix ratio for this motor. I have been using 50:1. I plan on taking the rig out on the lake real soon for a full test. I felt so good about the whole thing today I drank a daiquiri and went over to Boat Stuff and spent some money. <br /><br />Goco

 

[Chinewalker]

Re: 1967 model 20 hp Merc stator mystery.

Hi Goco,<br /> Great news! Glad to hear you've got her running again. 50:1 is fine with that motor, with perhaps another shot for good measure. Regular gas and TC-W3 rated oil...<br />- Scott