My stock '54 Merc quit running and I suspect the coil is the culprit.  I have no fancy test equipment but my circuit tester shows power to the plus side of the coil grounded to the battery and to the minus side of the coil.  I pulled the coil lead from the distributer and layed it next to the exhaust manifold and cranked the engine expecting to see plenty of fire from the lead jumping to ground on the manifold.  Nothing!  I tried a spare coil (condition unknown) and the results were the same.  I am gettig no spark at the dist. points as well, no surprise.  What am I overlooking?  I have a 7 function multi-meter but am somewhat unskilled in its use.
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I hate to buy another coil if the fault s elsewhere.  Any help?

You need to check that your points are connecting. When they get dirty and/or pitted they no longer connect the circuit from the coil to ground and the coil cannot charge up.

I disconnect the distributor wire from the coil and measure the resistance to the distributor body and also check across the points. The points need to be at the flat spot of the distributor cam. The resistance will be zero if they are good. If not ensure they touch. Clean them with a points file or sandpaper or if they look pitted, replace them.


1936 Ford 3W Coupe : 56 T-Bird 312, 47 Packard 3 speed, 40 juice brakes.
1968 Merc Cyclone FB GT 390, Getting a better front clip!
1977 Ford F-250 Supercab RWD Explorer Long box.
1976 Chev Camaro RS LT
Future rebuild : 1949 Ford F-1

Points are kind of funny sometimes, they did go away for some good reasons. They can get a layer of skunge on them, literally overnight, and stop working.

Not a big deal for motor heads maybe but definitely the first thing to look at, check for continuity to ground with a "test light". I like the "professional" ice pick kind with alligator clip, but you can roll yer own with a length of stranded bell wire soldered to an 1157 bulb and Bob's Yer Uncle. Don't buy another ignition coil unless it is proven defective. I bet more good ignition coils get replaced than almost any other part.

I can't tell you how many times I have suspected a coil was bad only to find some other problem. I also suspect bad points.   Chinese auto parts store points are often the cause.  Check both ends of the coil wire too. If you are using carbon core wires, they can burn and arc. 

The wire in the distributor that connects the points to the coil is known to break inside the insulation from the  flexing caused by the continuous motion of the vacuum advance. Its  insulation usually is still intact hiding the broken wire.

Thanks, guys.  I pulled the dist. cap, crawled into the engine house (gotta luv henry's y-block dist. location) with a flashlight to check the point gap and overall condition inside the dist. housing i.e. disconnected or broken wires, grease, poor ground, etc. and I found that the points were out of adjustment.  Re-gapped and replaced the condensor while I was in there.  Cranked it with the cap off and saw plenty of spark.  Closed it up and started the engine, runs like it should.  Having a little trouble with the auto choke and need to replace the spring.  Thats another day!

Likely explains my occasional miss I had previously blamed entirely on bad/old gas.  Time to check the points. 
‘Also, Sandbird’s post is a new one on me.  Interesting.  Will file it away.

6 VOLTS/POS. GRD. NW INDIANA

"(gotta luv henry's y-block dist. location)"

Wait til you get to be my age, Lanny!      While we're on the subject, I don't know what the Mercury shop manual says, but I think the '54 Ford manual (addendum) suggests that technicians remove the entire distributor to replace standard tune up parts - points, rotor, condenser.   I haven't taken that approach yet, but as I get older, I could see how it might be easier than with the distr. on the car....unless it's frozen in place like mine currently is.

It was kind of a deal for me to remove and replace the distributor cap the other day just so I could more easily read the dist. part #. (And it still wasn't that easy to read.) Oh well, it gives me a sense of accomplishment when I'm done!

JimNNN, I looked at your profile and it looks like a bit further over that proverbial hill, passed 70 a few years  Wrecked a few cars and fell off of a few motorcycles in my younger days, paying the price now.

Back under the hood again - stupid car and mechanic!   Got it running yesterday 'cause it quit again 2 days ago.  No power and can't get above idle without it snorting thru the carb and popping thru the exhaust.  Re-set the timing and the mixture screws and then found that the points are toast.  They were new 150 miles ago!

I may have to pull the dizzy again and do the repairs on the bench.  Depends on whether or not I drop one of the points retainer screws down inside the dist.  Ugh!

You might consider putting the ‘old’ condenser back in.  The new crop of condensers do tend to be a shot in the dark as to how good they are.  You don’t specifically mention if the car is now 12 volt or still the original 6 volt.  If converted to 12 volts, you’ll need a resistor going to the coil.

Lorena, Texas (South of Waco)