Re: No Spark on a '62 450
You have a magneto on your motor, it's a very basic ign and easy to work on. But before you tear anything apart, disconnect the wire going to the side of the the mag and crank the engine over. If the ign switch or internal harness were faulty, it'd kill spark. If that doesn't work, you're gonna need to pull the mag.
The magneto is held onto the drive assy by (4) bolts. You'll need to pull the spark advance/idle stop/throttle stop plate at the front of the dist to gain access to the back (2) distributor bolts. Note the position of the mag as relates to the distributor drive. The driveshaft has a flat spot milled into it, so it only goes back into the drive one way.
Be mindful of the 'plastic' parts (cap, rotor, cover plate) as they are likely to be fragile in their Old Age. The rotor will just pull off with your fingers, it shouldn't take an excessive amount of force to do so. Also note what screw goes where, some are specific length for their location.
The most likely cause of No Spark in a magneto is 'hazed-over' points. Before you spend a ton of money on parts you might want to remove the points, clean the contact surfaces to bare metal, and reinstall. Gap points to .008"-.010".
You can test for spark with the mag removed. Just lay the shaft of a screwdriver on the metal case of the mag. Hold the end of the screwdriver about 3/8"-1/2" away from the flat copper strap coming off the ign coil. Give the magneto shaft a stout turn in the CCW direction (CCW as you're looking at the shaft). You should have a strong spark jumping the gap.
Caution: be sure the screwdriver is firmly grounded to the case, and don't touch the coil output, or you'll be the one jumping!!!!
If not, check the kill wire connection going to the side of the case for grounds. If someone in the past assembled the insulator incorrectly, or the parts have deteriorated, it can kill spark.
Another thing to check is the ign coil. Held in by the allen screws at the end of the case; remove these and the coil pulls out. Inspect for cracks or arc marks, if you find them the coil is bad. Used ones are available on eBay etc.
If you have a good spark, you might just want to slap 'er all back together and test run before you spend more buck$ on parts. That way you can evaluate whether it'll be worth putting the money in 'er to bring back to full glory.
One place I know of that carries a lot of parts for old Mercs is (no surprise)
www.oldmercs.com
You'll find tuneup parts etc there to maintain your motor. The more commonly-used parts such as impellers, seals, etc are still available from factory and aftermarket sources.
You should also be able to find some parts here at iBoats. Other parts places with good diagrams are
www.boats.net ,
www.crowleymarine.com , and
http://www.mercruiserparts.com/SelectModelType3.asp?class_id=2
HTH & let us know how it goes..........ed
p.s. service manuals are Good!!!!
