Hey y’all, I have a 70 F100 pickup with a 240 straight 6, 3 Speed on the column. I recently did a complete tune up (plugs, wires, cap, button, points, condenser, coil). Ever since I changed the coil I keep burning up condensers. I was told that it was the right coil at the parts house 🙄. Anyway, question is... should I just go with this coil and add a resister or find the correct coil? Thanks in advance!

 

Where are you getting the ignition condensers? What brand? It is difficult to get serviceable points and condensers these days. The condensers in particular are especially bad. Right outta the box bad. Ford (Autolite) or Motorcraft are what you want to use if running a contact point ignition system. NOS from 20 or 30 years ago, but condensers go bad over time, they absorb moisture or deteriorate, short out, they no longer "hold a charge".

There are a lot of tiny though loom important "gotchas" in making the ignition system work correctly and reliably. That's why electronic ignition supplanted it just as soon as it became practical.

A point system has what's called a divider network in the primary circuit. The ignition coil primary winding has an ohms resistance of about 1.5 ohms. The RUN circuit has an additional ohms resistance of about 1.5 ohms, for a total of about 3 ohms. This keeps the points from burning up due to excessive current or arcing. Make sure the primary coil winding is 1.5 ohms or thereabouts, and the "ballast" or "pink wire" in the wiring harness is connected. And find a Motorcraft ignition condenser if you want to run ignition points. And a Dwell meter. And distributor cam grease, and an inch-pound spring scale, point file, and .. and ..

 

Pertronics and a flame thrower coil and be done looking under the cap.

 

Why replace the coil?
That was never part of a tune up and only changed if it was found faulty.

The same was also said of condensers. If the points did not have any deep pockets then just reuse the condenser.
I would replace the condenser all the time anyway LOL

Put the old coil and condenser back on and see what happens.
Dave ----

 

It was generally considered "good practice" to replace the ignition condenser as part of a routine Tune-Up, usually twice a year, BUT, lot of savvy guys would specifically not replace the condenser, if the ignition was otherwise working well. And that was when people drove 15,000 or 20,000 miles a year. Even today people will sometimes say "They are cheap, just replace it."

Well the problem is much worse today, the el-cheapos are so cheaply made and don't last if they even work at all. A good quality set of points and condenser will last a heck of a long time in a collector car or truck, years and years.

 

What's the primary voltage on the new coil? What are the o high ohms? Did you bypass the stock resistor wire?

 

Just buy new Ford Motorcraft condensers from your dealer as they are US made if you want to keep your points. The Ford tractor guys are having the same problems with them being made in craptastic China, and there is just Case New Holland.

 

The last condensers sold by Ford that were USA made was pre 1994.

 

The last condensers sold by Ford that were USA made was pre 1994.

 

Condensers (capacitors) have a shelf life, depending on their construction. So even the good ole' U.S.A. versions aren't necessarily going to be good. And to test them before installation need to apply about 500 volts DC on them. Most people today don't have the equipment. That's probably why mechanics often left them alone, back in the day.

The Model T guys and others have had good results using modern high voltage, high current poly film caps. Good ignition is critical and the condenser is key to that in points ignition. I found in testing even the NOS examples, while they passed the leakage test they don't seem to "hold" voltage. A large capacitor can be charged up, sort of like a battery. It will zap ya if you pick it up the next day. Of course all this stuff is "interesting", but it's easy to see why people just install electronic ignition. But if you're determined to run points you'll have to make sure whatever condensers and points used are good quality.

 

Last "new" condenser I bought was at Autozone and it lasted 100 miles, barely. I found an old rusty one in my roll away and used it for a few years before finally put in a Unilite.
You can't buy anything worth a hoot today.

 

Turns out it's fairly tough to manufacture a high voltage, high current capacitor in the small metal package designed to fit inside the the distributor. At least at a given price point.

But there's no electrical requirement they have to be inside the distributor itself. This used to be common, they were installed externally. The sprague 600 volt 0.25uF "orange drop" is pretty chunky but it will fit inside a Ford distributor. These seem to work excellent, and are light years better than the elcheapo POS sold at the auto parts stores. The capacitor should be supported somehow to prevent the leads from work hardening or breakage due to vibration.

 

A Pertronix doesn’t fix a worn out distributor. If the dizzy is original, I would replace it with a reman.

 

I'm agreeing on the worn out distributor! With a reman and a Pertronix II under the cap, no one would know. You can also get the Flamethrower II coil in black. I really like my Pertronix II setup!

 

When I was in Automotive trade school the first thing I learned is not to catch something if someone would say “hey catch this”. They would lay a condenser on a engine and put the wire in a spark plug wire then start the engine. Sometime someone would tape one to the light switch in the bathroom.
The thing that convinced me about electronic ignition. We had a Sun Tune machine, when you looked at the dwell line on the oscilloscope you could put a straight edge on the step of the line with no movement. With points the step continually moved a few degrees.