Welcome to the Corvette Forums at the Corvette Action Center!

The Problems With Points And Why They Were Obsoleted

Joined
Mar 9, 2009
Messages
1,026
Location
Yemen
The breaker points that were used from the 1940's thru the 1970's did the job they were intended to but not very well. The first problem points caused was sideways wear of the upper bronze bushing in the distributor housing which made the timing increasingly erratic. The next problem is every time points open (break) there is a small electrical arc that burns the surface of the points and leaves a little bit of carbon residue which often prevented the points from closing. You'll notice when using a timing light on an idling engine the light doesn't fire every time but rather about 9 out of 10 times because the carbon prevented the points from making contact and charging the coil. At a higher rpm the points got closed faster (and harder) which helped the problem but didn't eliminate it. So the points had to be replaced by the HEI style that uses a proximity switch to charge the coil.

If your C3 is still using breaker points you'd be much better off converting it to a Pertronix or similar system to avoid the constant miss-fire that points cause.
 
Joined
Mar 9, 2009
Messages
1,026
Location
Yemen
Now tell us the real reason GM switched to an HEI distributor.


There were several reasons why all of the world's manufacturers abandoned breaker points:

1. To eliminate the upper bushing wear caused by the side thrust of the points

2. The breaker points often failed to charge the coil because of contact burning

3. To eliminate the constant maintenance and/or replacement of points

4. The HEI was needed to fire the increasingly leaner air/fuel mixtures
 

Vettehead Mikey

Well-known member
Joined
Aug 26, 2003
Messages
3,486
Location
Not that far from Ottawa
Corvette
1973 Coupe
There were several reasons why all of the world's manufacturers abandoned breaker points:

1. To eliminate the upper bushing wear caused by the side thrust of the points

2. The breaker points often failed to charge the coil because of contact burning

3. To eliminate the constant maintenance and/or replacement of points

4. The HEI was needed to fire the increasingly leaner air/fuel mixtures

You get half points for answers 3 and 4.

Not bad.
 
Joined
Mar 9, 2009
Messages
1,026
Location
Yemen
You get half points for answers 3 and 4.

Not bad.


Well, half points are better than no points so I'll take that as a compliment.

The fact is breaker points caused constant miss-fires; especially during idling and that's why the timing light would show an intermittent miss-fire. The module that replaced them was a much more reliable trigger as long as it's a quality module which brings up another problem; Chinese modules that have a very short life span and will leave you broken down on the side of the highway. So when it comes to modules pay the price for a GOOD one. And as of several years ago I started using Permatex Ultra Black RTV instead of the grease because I believe it transfers heat much better. The grease gets real hard after being exposed to heat cycles so that's why I'm experimenting with the RTV.
 
Joined
Mar 9, 2009
Messages
1,026
Location
Yemen
I remember in the mid 70's I started finding pickup truck rotors with holes burned thru them and constant module failures. That's when we first heard the term "Dielectric" which referred to plastics that would resist high voltage leakage thru them. So while the HEI was a great idea it took the world's manufacturers a while to develop new plastics to deal with the higher voltages. Now days it seems the biggest problem us C3 owners deal with is inferior Chinese modules that don't last very long. Because of that I keep two new modules in my C3 along with a good set of tools for roadside repairs.
 
Joined
Mar 9, 2009
Messages
1,026
Location
Yemen
Dirty (Burned) Points

As long as points are new and shiny they perform very well. But as they get burned more and more they become less and less accurate at charging the coil. That's why the proximity switch and module triggers used today are far superior as long as they are made from quality components. I clearly remember the days when I was setting the timing and watched my timing light fail to flash every time. It was dirty (burned) points causing those misfires and those misfires were certainly happening while the car was in motion.
 

Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors

Dealers:

MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Parts/Accessories:

Vetteskins

Advertise with the Corvette Action Center!

Double Your Chances!

Partners

Top Bottom