Re: 1964 Mercury 500 no spark plse help
The distributor is a self-energizing Magneto-type. Has a set of points, condenser, rotor, magnets, distributor cap.
The Magneto is driven off the flywheel via a toothed belt and sprocket. There's a specific alignment for this belt so don't take it off the pulley on top of the drive assy unless you note the alignment marks first.
There's an arrow cast into the small driven pulley, which when aligned correctly points to a line or set of punch marks on the O.D. of the flywheel.
There's one wire connected to the magneto on the outside; this is the "kill" wire. When the ign is "OFF", the "kill" wire is grounded which kills spark. When the ign switch is "ON", the ground path is removed and the mag sparks.
Note the most common problem with old Merc mags is dirty points. If you're having spark issues and want to service the points, separate the mag from its drive assembly by removing (4) bolts holding the mag in place. The mag has a splined shaft with a flat machined onto it, so don't worry about getting it out-of-whack upon reassembly. It can only go back one way.
There are (2) screws with locking tabs which hold the distributor cap to the magneto "cover", remove these and very carefully pull the cap off. Be careful with this stuff 'cause it's old and easily fractured.
With the cap off you'll see the rotor inside the cover. The rotor just pulls off too. You may need a bit of force to pop the cap loose but again, be mindful of the fragile parts!
(4) more screws hold the cover, once it's off you'll see the mag's innards.
If the points don't look too pitted, you can clean them on a whetstone, burnish with crocus cloth then reassemble and gap to .008"-.010". Note that you can't just run a piece of sandpaper in between the points contacts and expect to clean them up adequately. To do the job right, remove the points, disassemble and clean each contact to shiny metal.
If the points are in very bad shape or pitted badly, replace them. Also replace the condenser.
That's just the most basic description and hopefully answers your underlying question(s). Recommend you pick up a good service manual if you're considering working on your Classic Merc. Also consider installing an impeller once you figure out if she's worth messing with or not.
Meanwhile, here's some Good Ol' Mercury service info that'll keep you busy for a while!
http://www.maxrules.com/fixoldmercindex.html
Cheers.............ed
