Any distributor machine users here?

[Dave Koehler]

I would like to have a better idea of what is required for a logger and/or scope to be hooked up to read the degree point, etc.

The chair. Well...A+ to the guy for using what was on hand. Green at it's best.

[Lockwire]

Lap tops, throttle stops, races that only last 7 seconds, what is this world coming to? Your advance curve probably retards. You still need to apologize to the gentleman for casting aspersions upon his distributor chair. The shock therapy burns holes in my tinfoil hat.

I agree with Tuners retard opinion, many electonic ignitions do not do what people think they are doing. Stuart.

[David Redszus]

I still use a Sun distributor machine. It is old and I have rebuilt it several times but it is worth its weight in gold.

Vintge cars, lots of old production based sports cars and a whole lot of other engines still use distributors. Some are points triggered, some magnetic induction and some Hall Effect triggered.

I have added two additional features to my distributor machine. One is a chamber, pressurized with shop air, fitted to fire spark plugs. The second is an oscilloscope. I can read the spark traces while the chamber pressure builds. At some pressure and distributor speed the ignition system begins to misfire. Very often this occurs with high tech systems at operating speeds much lower than I ever imagined.

It is also useful to test advance curves produced by programmable ignition systems, to test coil output, to check RFI from secondary wires, to check for point bounce, to check for firing interval and jitter, and to test rev limiters.

Other than that I have no need for a distributor machine.

Dave I have been thinking about adding a chamber to mine. Do you have any pictures of yours??? I was going to use some heavy wall box tubing and cut out a window for lexan on the front of it. What type of PSI do you run in yours??

Keith

While there is provision to fire up to 8 spark plugs, I only put one plug into the pressure chamber. The spark traces on the open air plugs can be seen visually, although a magnifying glass helps a lot.

For a pressure chamber I used a short length of steel pipe, threaded at both ends. Both ends are sealed with caps. One end is drilled and tapped for a spark plug the other drilled and tapped for an air hose quick connect fitting. Be sure to properly ground the chamber.

The chamber is hooked to shop air with an inline pressure gauge. The most my compressor will develop is about 120 psi gauge. Most ignition systems begin to misfire well before that pressure is reached. For a 12.5:1 geometric compression ratio, a cylinder pressure of about 85 psi is developed at a firing point of 30 degrees. So higher chamber pressures are really not necessary.

The scope traces will reveal misfires, irregular spark plug patterns and spark duration. I use a timing light with an advance meter to determine ignition advance degrees and dwell.

Once you have begun to examine the characteristics of real ignition systems (meaning all of their shortcomings) you will never trust an ignition system again without testing it. Never mind what the product sellers may say.

Hype does not make power.

[k-star]

How about the oscilloscope, is there anything special i need to know about buying one??? Can i use any of them or do i need an automotive type??


Keith

[David Redszus]

How about the oscilloscope, is there anything special i need to know about buying one??? Can i use any of them or do i need an automotive type?? Keith

I would check ebay. There might be a number of older, unused, engine analyzers available. Some of the new Fluke meters have the capability to display a scope trace.

In the end, any type of scope will do. In the early days I used a home built Heathkit scope. Now I use a digital USB two channel recording scope linked to a laptop.

[jmarkaudio]

Lap tops, throttle stops, races that only last 7 seconds, what is this world coming to? Your advance curve probably retards. You still need to apologize to the gentleman for casting aspersions upon his distributor chair. The shock therapy burns holes in my tinfoil hat.

I agree with Tuners retard opinion, many electonic ignitions do not do what people think they are doing. Stuart.

Actually mine does retard, on purpose. And probably not much tinfoil left on that hat... Tuner and I are just busting on each other.

[Tuner]

Retarded or not, jmarkaudio could probably tell us about some good software that turns a PC into an oscilloscope. He probably has it in his tinfoil pocket protector. There is some open souce stuff on sourceforge.net.

[Dragrace]

FYI i have a Sun 500 for sale PM me if interested

[MadBill]

Per David's post re pressure testing of systems, it's useful to know this is a 'worst case' test, as a combustible fuel/air mixture is significantly more electrically conductive than pure air (and if you don't have the former, you don't need a spark!

[bill jones]

-I have several hopped up distributor machines and while some people use compressed air to load the sparkplugs---I simply use a quickly adjustable spark gap plate.

-I make a circular plate out of phenolic--mounted 8 pointed screws down thru the phenolic similar to a large diameter distributor cap---where I attach the plug wires to those screws.

-I use a grounding plate with 8 more pointed screws directly underneath the phenolic plate screws----to create a minimum gap of about .200".

-then I made the phenolic plate adjustable upwards to increase the gap to about an inch.

this allows me to test at about any gap I want in open air--and the wider the gap the easier it is to find the weak links in most distributor type ignition systems.

-the gap I've come to consider necessary for decent race quality on a battery powered ignition is about .690" or so.

-Any 8 cylinder system that'll fire those 8 gaps in open air (at 4200' elevation) without the spark errantly running off anywhere to ground or to any one of the other terminals has proven to be a pretty high class system.
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-The problem is the spark usually needs a lot of attention to details to keep it all under control and going down the proper paths to the wanted grounds.

-One thing I found important is to ALWAYS test at night when you can turn the lights off---there is stuff happening that you can only see at night.
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-here's a link to very simple and very common problem that cause many racers grief and they seldom ever find this sort of stuff until somebody with this sort of testing experiences shows them where to look.

http://ryanbrownracing.com/Bill_Jones_Page_11.html

[David Redszus]

Per David's post re pressure testing of systems, it's useful to know this is a 'worst case' test, as a combustible fuel/air mixture is significantly more electrically conductive than pure air (and if you don't have the former, you don't need a spark!

Bill is right, this is indeed a worst case test procedure; by design.

An air/fuel mixture is not electrically conductive utill it ignites and ionizes the mixture. An increase in pressure will require an increase in voltage. An increase in temperature will reduce the required voltage.

An increase in plug gap will increase the required voltage and reduce spark duration and vice versa.

One thing I found important is to ALWAYS test at night when you can turn the lights off---there is stuff happening that you can only see at night.

Bill Jones is right on. It is very, very informative to turn the lights off on the dyno cell at night and watch the electrical lightning storm dance around the ignition system. After you see the uninvited external spark traces it makes you wonder how the engine ever ran at all.

[Ron Golden]

I've been recurving distributors for years on an old Sun 400 machine. I can do point, HEI, MSD and any electronic distributor. I've made several thousand dollars with it. I think recurving the distributor is one of the most important things that can be done to an engine.

My partner and I recently tested the Electromotive ignition system to 13,000 rpm @ 300 psi and the Electromotive system worked great. Needles to say this wasn't done on the Sun machine.

Ron

[GaryFB]

Excellent topic, but the original innovate link does not work. Has anyone modernized their distributor machine?

[David Redszus]

Excellent topic, but the original innovate link does not work. Has anyone modernized their distributor machine?

Might I ask, what do you mean by "modernizing their distributor machine"?

Recently completely rebuilt my Sun 504 distributor machine, replacing the vacuum tube, selected capacitors, bearings,
drive belt, etc. The Sun 504 is connected to a J & S ignition box that can accept point trigger signals, magnetic, Hall effect, and can drive a Bosch Red coil. It also can display the spark traces via a USB scope. The spark plug pressure chamber was discussed earlier.

What else would you like to see added?

[rebelrouser]

I taught automotive at a college for many years, we had a lot of different scopes. The easist scope to learn and use for the students was a Pico, it uses a computer. It is a high quality tool. Some of the cheaper scope PC type tools are junk so be careful what you buy.
https://www.picoauto.com/products/autom ... s-hardware

Another option is to go to Ebay, And buy a used Snap-on Modius with a scope is fairly cheap, and a decent scope. That is what I have at my shop. Snap-on does not support the scan tool part any more, but still sells leads and such for the scope. My scan tool works to 2010, which gets 99% of the junk I work on anymore.

I also am interested in upgrading an old distributor machine. I have a bench top machine, army surplus and it works, but the lights that flash so you can watch it advance are a little dim, got to use it with the light in the shop off to see it right. I mainly use it to test distributors and ignition boxes. I use a spark gap tool, but a cylinder under pressure would be the best way. Used to have a spark plug tester that pressured plugs with a window years ago, so you could watch the plug fire, as pressure increased.