One of the basic conclusions from years of combustion research is that once you have enough ignition energy to consistently light the fire, additional energy will not make any difference in performance. That's why Lar's tests showed the same power with a properly functioning Delco single point system relative to electronic systems.

Note that I said energy. Big voltage coils are meaningless because the spark bridges the gap at about 6-12 KV and then drops until ignition energy is consumed. If the coil can generate 20KV open circuit it will fire the plug. A 50KV coil will just ruin the ignition wires if the plug won't fire.

The distributor is probably the most overlooked component on engines, but if you overhaul a single point - shim up the end play, make sure the bushings are snug, have a good wobble free breaker plate, and use the 28-32 oz. points for engines with redlines over 5500, it will work just fine.

The other advantage of the single point is that it is SIMPLE and very RELIABLE. If they misbehave they can usually be jury rigged to get home, and the simple expedient of placing an old set of functioning points that was set to the proper dwell before being removed in the glove box with a flat blade screw driver will virtually guarantee that you will never be standed by ignition failure.

The HEI in my Cosworth Vega has standed my twice (module once, pick-up coil once) , but it takes a hell of a beating from the second order unbalanced vertical shaking force at 7000 revs. I now carry a spare HEI dist in the spare tire drop center and a 9/16" wrench, so if it ever takes a dump again, I'll be back on the road in five minutes.

It took me years to get the single point in my SWC to function properly, and after installing the TI from the "12 mile L-88" and having it fail twice in eight years I finally reinstalled the single point, as I had found out the secret to making it work properly to 6500 revs - shim up the end play to two to seven thou, a new wobble free breaker plate (the bushings were okay), and the 28-32 oz. points.

Check the dwell every few thousand miles, and replace the points every 15K, but they will usually last twice as long. It's just part of a tuneup on a SHP engine - points, plugs, and valve adjustment. One of the best things about vintage cars is that you can do the minor maintenance with simple, basic hand tools and trouble shoot anything in the electrical system with an inexpensive multimeter.

The industry went to electronic ignitions because a misbehaving single point system can overheat catalytic converters, and they seem to have designed the electronic systems so they either work perfectly or don't work at all. At least that's been my experience.

Duke

 

Why would a regular points type system burn out in 1,000 miles or less? I would buy all the best brands of points and condenser, and still get the same results. Even changed the coil twice and checked how much advance came on at what rpm. I finally gave up and put a pertronix system in there and have had no problems since. Anyone have any ideas?

 

Lars,
What brand/PN are good points and ignition coil???

Very good and informative post!!

 

I'm going to my 2 cents in here! I run Pertronix Ignitor breakerless conversions in my Vettes. My LT-1 made 443HP with just a Pertronix IgnitorI conversion and their coil. I have used these conversions in my cars for over 15 years without problems! The best ignition points are Echlin brand at NAPA autoparts stores or Accel brand at the speed shop (same company.) The cost of a replacement set of points is now over $20, my Ignitor is about $60. The LT-1 in my car will turn 7,500RPM to be stable, a set of ignition points will have to have a HD breaker spring and have poor wear properties. Many people do not realise that the high performance Chevy's like the Z/28 and L78 396 cars had special profile breaker cams in the distributor for high RPM stability, this caused the contact set to degrade more rapidly than a the normal breaker cam. I remeber changing points out in my 69 Z/28 Camaro in less than 5,000 miles because it was missing in 4th gear at the Wedensday night Drag races. NAPA and Accel still have HD high RPM contact sets if you must, the following is a remebered sequence: CS786=std contact tension, CS86=mid tension, and CS7860=SUPER HIGH tension as used by Bill Jenkins in his Pro Stock stuff before reliable electronic distributors were around. To pacify every one, I do carry a set of points/condensor for the day that my Pertronix decides it dosen't want to work anymore, I've been carrying them for the last 15 years!

 

Probably the biggest difference is that you have to know how to setup and maintain a points system. An electronic system is generally plug and play. This doesn't make you lazy, it just makes you practical. I'm a "weekend" mechanic, and don't work on cars for a living. For some of us, enjoying the cars means NOT having to fidle with them to get them "just right." I say go with what you know, and if you can set up and maintain a points system, and you WANT to do this, than you should! If you want ease of maintenance and generally better reliability, but are okay running the risk of a complete failure coming out of the blue, then go with a newer electronic system. That's just my 2 cents.

 

:iagree: Exactly how I feel. I can't fiddle with them every month. Rather be driving...

 

Duke,
You make an excellent point re endplay. I do not have the technical expertise of many members but I have had occasion the rebuild four distributors, both HEI and points types. Among the four, I have found that typical original endplay was 0.018" to 0.025". I snug those down to ~0.007" with the appropriate shims. I have no doubt that this will lead to increased reliability of the ignition system; be it points, HEI or aftermarket modules.






[Modified by paul67, 2:03 PM 2/6/2004]

 

Lars,
I used to Run Mark 10 CDI units in conjuction with point on my 68 Camaro and my dad's 65 Impala. We still have one on a 72 Scout. They definitly extended the life of the points, but they did wear out. My biggest problem with points was that the contacts would get stuck together and eventually torn off on a car that wasn't driven very often. The Mark 10's on the 65 and the 68 eventually wore out, they were nearly 30 years old. I replaced them with a stock GM HEI distributor and have been fine ever since.

I don't think anyone disputes that non-points systems give you more horsepower, if they do it's the CDI box doing all of the work. Non points ignition systems are definitly less maintenance if you have a good one.

I ended up putting a full MSD ignition in my Vette and have been orgasmicly extatic with it.

P.S. I'm 26 and I own and know how to use a dwell meter, does that make me special? :D :D