Re: 1962 Mercury 850 no spark on all cylinders
Pull the coil wires off the coils and check for spark from each coil. If you have a spare chunk of spark plug wire you can do the test easily, plug into a coil and adjust the free end so that it's approx 3/8" away from a grounded portion of the block or cowling. Crank the starter over and you should see a fat spark.
If you don't have an extra piece of wire, pull the coil wire going to the center of the distributor cap (NOTE: this wire inserts into the coil directly, but is unscrewed from the dist cap, don't "pull" on the cap end as you may damage the wire).
If you get a strong spark directly out of both coils, likely there's a problem with the rotor. If one section of the rotor is grounded it'll kill spark to the even or odd sets of cyls such as you're experiencing.
If you still don't get spark on 1,3,5, the most likely suspect is the points. Either contacts dirty or gap closed up. The distributor assy containing the points etc is removed by pulling the 4 bolts holding it to the distributor drive. You'll also need to pull the bolts holding the idle stop/throttle stop/spark advance bracket and remove bracket.
One final thing you can check to confirm points would be to disconnect (at the terminal board on the side of the motor) the brown and white wires coming from the distributor. Then attach a test lite or ohmmeter to one wire, the other test lead to ground, and turn the flywheel thru several revolutions. You should see the lite go on and off as the points close (or low ohms then infinite reading).
Try this with both wires, if you find one has no continuity, the set of points connected to that wire is not completing the circuit and that's the one not sparking.
I can't recall if the brown wire or white wire feeds the points for cyl's 1-3-5, I bet one of the other OldMerc Guru's with better memory than me can tell ya fer sur!
NOTE: remove the 2 screws holding the side coil wire adapter to the dist cap before pulling the cap, or you could damage the spring-loaded carbon contact in the adapter.
Disassemble the dist and points, clean to bare metal with a whetstone or appropriate abrasive sandpaper on a flat surface, burnish with crocus cloth then reinstall & adjust them to approx .010". This will get you running but she'll run & idle so much better if you adjust the timing dwell IAW these instructions:
http://www.maxrules.com/timingindex.html
You can make your own pointer and dwell scale, someone on this site has a .jpg or .bmp file of the pattern for the dwell scale which would make it a lot easier.
Anyway, that should give you something to look at, let us know how it turns out.........ed
