Technical Adding CDI to Points Ignition

Never done this, supposed to take the current load off the points so they last much longer. Maybe a hotter spark too? Do the MSDs do that too? Is there an OEM one that can be added?

 

CDI ignition amplifiers, designed to be used with points, have been around a long time. I don't know of any OEM, but MSD will certainly do it. And probably give a hotter spark, if you need that for some reason (OEMs did when they went to lean mixtures and other things in the mid 70s, so they started using HEI, etc)

If you have issues with points wearing out, in the modern world, you are doing very well. Most of us don't put enough miles on them.

 

I'm not sure, but I'm guessing non-CDI versions were more common than CDI versions. CDI systems work in a different way, they charge a capacitor to a few hundred volts and then almost instantly dump that charge into the ignition coil when it's time for spark. That voltage boost requires more advanced electronics = most likely costs more to make.
A conventional ignition amplifier just switches the current to the coil on or off just like points, but it uses electronics to do that. Turn the current on to "charge" the coil by building up a magnetic field in it, turn the current off to collapse the magnetic field to cause a voltage spike = spark.

Both types can be triggered by points or more modern sensors (optical, magnetic and so on) that doesn't wear at all, they just have to be designed to work with whatever type of trigger you want to use. CDI tends to be able to produce more sparks in a given amount of time, i.e. it can handle higher rpm, especially in engines with many cylinders. As rpm goes up, conventional systems eventually run out of time to build up the magnetic field in the coil = less energy available to make a spark.

 

The switching power supply to make that high voltage, used two big transistors, you can plainly see them on many old CDI boxes. Here's the Delta for example, the big things on top are the transistors.

 

That's cool, I remember seeing those. Wasn't the Judson also a CDI or amp?

I am hoping to take some trips this year in the '56 Vette with factory dual point. I probably don't need one, just thought it'd be an easy addition without any down side and a possible up side.

 

I haven't had to mess with points on the long trips I've taken...but did have a condenser go bad once, so make sure the condenser in the car is really old, not a modern replacement. They don't make them like they used to.

 

You can also use a Chrysler ignition module from the mid 70's. They are easily triggered by a set of points.

 

Interested in this^ Anybody have more details on what it takes to do it?

 

The Chrysler unit pretty far down on the list of ignition modules I would use....I guess I've just had too much experience with them.

 

https://www.jalopyjournal.com/forum/threads/cdi-who’s-running-‘em-on-their-hot-rod.1217252/

 

I used an MSD box with points successfully for many years. The issue is modern points and condenser sets suck, particularly the condensers. My advice is to stick a Pertronix in there and get on down the road.

-Abone.

 

I put an "electronics" condenser on my Chevy II, it's been fine for years. And the other old cars with points I've driven, I left the old one in, and they've been fine also. It's just the replacements made in the past 10 years or so have problems. I use old points, just clean them up with a file and set the gap and add a tiny dab of cam lube to the part that rubs the cam.

 

CDI ignition was first used on two stroke boat and bike engines were it's high voltage prevented plug fouling.. The spark duration is shorter...That may be an issue so that's why CDI's can be a multi spark at lower or all rpm's.
I tried various ignitions in my moderately modified GMC 302 in the 37 chevy truck. Points, GM HEI and points with a Mallory 6A multi spark box...By seat of the pants they all performed the same at full throttle...But a low rpms the GM HEI could fire a larger plug gap that cleared up a slight lean bog ..
If you got an engine running 20 pounds of boost or a load of nitrous , a high output might be necessary..

 

Dang I tried CDI in the search box first, it didn't know what the heck I was talking about.

 

Ford TFI to replace points
FORD TFI electronic ignition.pdf (49ccscoot.com)

 

A TFI doesn't replace points, it's triggered by them. I'm running one in my car now. I learned about here on the HAMB. The copy of the article you posted is laying on my bench because I just re-read it today. I need to clean up my wiring a little since I moved the module to a new location recently.

Gary

 

My mistake. That is what I wanted to say.

 

Such a sad but true statement, just like tradesmen.

 

I believe @tubman ? sells replacement condensers.

 

Running a Winterburn CDI on my 40 Coupe with a 53 Merc for a while now. The points will never wear out because they are just a trigger.
There’s a thread on here somewhere.
https://www.jalopyjournal.com/forum...on-their-hot-rod.1217252/page-2#post-13993400

 

Not quite correct. The points wear in two ways. The contact points wear down and that should be reduced to very little wear when using an ignition amplifier = VERY long life.
However, there's also the plastic(?) part sliding against the cam that opens the points. This also wears down, that's why you need to adjust the gap on the points every once in a while, eventually you run out of adjustment and need a new part.

 

Of course...

 

So with a CDI are the condenser and ballast resistor still used and relevant?

 

From the Delta instructions

 

As the CDI system works in a completely different way I see no use for them after the swap, but follow the instructions to the exact system you use. As with other types of upgrades where you replace parts of a system and retain other parts there can be different approaches to how it's supposed to work. For example, capacitors (condensers) are common components in electronics to dampen electronic noise. You get loads of noise from the sparks so there may very well be some components there to dampen the noise and minimise false triggering, someone may have thought it a good idea to save ten cents and keep the condenser instead of putting a new capacitor in the electronics box...

 

Chrysler module $35 NAPA http://www.gofastforless.com/ignition/points.gif

 

My distributor has no felt wick for lubricant and doesn't look like it ever had a mount for one (it has one big Mallory condenser outside instead of the internal ones). Is there a preferred lubricant for the rubbing blocks? Maybe some felt over the rubbing blocks?

 

Not sure, but I read that Bosch Heißlagerfett Ft1v4 is made for that job. I've never used it.

 

Like Jim stated, a dab of cam lube works real well.