This is a question for someone who has dealt in detail with their 400i Marelli S158C distributor. I have a Euro (single distributor) 365GTC/4 that has been modified to use the S158C Marelli distributor. It's a nice modification in that it does away with phasing/timing of four sets of OEM C/4 points. I am not sure how well the advance curve is working on this distributor, so I took it off and want to run it on my distributor testing machine. The issue is that this distributor uses a Hall Effect sensor with a distributor-mounted amplifier (so I believe), and I don't want to blow up the amplifier while testing the distributor on my distributor testing machine. When the ignition key is on, the ignition lead to the amplifier (when the distributor is mounted in the car) shows 4VDC, not the !2VDC I expected. There are just two leads to the distributor, and the other one that anchors to the S158C housing shows as a ground lead when measured with an ohmmeter to the body of the car. How do I run this distributor on my testing machine without blowing up the amplifier? These amplifiers are unobtanium. Thanks, Wil Image Unavailable, Please Login
A Hall Effect device will produce a voltage spike when a magnetic field is applied at right angles to the current flow. Think of it as a variable resistor where the resistance goes down when the correct magnetic field is present. The sensor output is shaped and processed by suitable circuitry, then used to trigger a switching device such as a thyristor, which switches a large current through the coil. My guess is that you are reading the output of the device with no magnetic field present. Is the input into the sensor 12V ? If so, I think you will see a 3 or 4 V spike when the rotating element passes the sensor. You can go here for a description and application of Hall Effect devices: http://books.google.com/books?id=R8VAjMitH1QC&printsec=frontcover#v=onepage&q=&f=false I'm not familiar with this particular distributor (I know the type 159 intimately). Does it have a mechanical advance under the base plate?
What type of dizzy testing machine do you have? Mike Florio and I both have Allen machines and these machines use a 6V coil to fire the strobe light on the timing wheel. Your worry may not be for the dizzy to blow up, but your testing machine. I don't know what Sun machines use, but they may be 6V too. I run CraneCams XR700 electronic ignition and had intentions of modifying my machine to run the 12V but it turned out to be quite complicated... What I have done in the meantime is I have another dizzy body with points, so I take the advance unit out of the dizzys from the car and put it in that and use that set-up for the testing machine. It's worked out well that way.
Mike/Peter, I confess to asking the question before fully tracing out my ignition system. My Marelli S158C distributor triggers an MSD 6A (P/N 6200) ignition module, see attached 6A hook-up diagram. If the diagram is too hard to read, go to http://www.msdignition.com/forum/index.php and you will have the same diagram on the cover page. It's a big .pdf file. So that means there is no amplifier in my distributor, it just has a magnetic pickup coil with two leads. These two distributor magnetic pickup leads attach to the violet & green leads of the 6A, which are the leads used by the 6A for a low voltage trigger source. The 6A orange & black leads then connect to & trigger my normal two-lead coil to create spark. The 6A white lead is not used, couldn't even find it in my installation. I have a Sun 404 Distributor Tester which has just two leads to hook to a distributor under test, a 'Ground Lead' and a 'Distributor Lead'. There are no separate power supply terminals or anything else on the 404. The trigger coil for the neon light is a black four lead unit buried in the machine that I know nothing about. My tester is set up for points only distributors, I believe I need a separate Sun or other amplifier to sense the low voltage S158C trigger output signal and drive the 404 tester strobe light. Image Unavailable, Please Login Image Unavailable, Please Login
Will: I'm not familiar with he internals of the Sun tester, but my Allen has a complete 6V ignition system built into it, including a coil. One side of the coil primary is connected to the power supply, the other side is connected to the distributor points. When the points are closed the circuit is complete (The distributor is grounded) and the primary builds a field in the coil. When the points open the field collapses and throws a jolt out the top of the coil. This jolt is routed to the flash tube on the rotating plate of the distributor machine to indicate where the spark occurred on the degree wheel. You need to determine how your Sun generates the flash to the degree wheel. If it works like the Allen (has its own internal ignition system) you might need to bypass that because the coil primary switching isn't done by points, it's done by the hall effect sensor triggering the MSD box. If that is the case, you could lay your ignition system out on a bench - the MSD box and the coil. Then dig around inside the Sun box and find the lead that fires the bulb - it will be a spark-plug type lead from the top of the coil, and connect that to the top of the MSD coil on the bench. That secondary jolt is 15-20KV or more so be careful how you route the wire. I've been thinking about modifying my Allen to us a high-intensity LED instead of the flash tube. LEDs are instant on-off (unlike any incandescent) and operate on 3-5V at up to 1 W, so it wouldn't need that whole 6V power supply (which in my case has tubes! Yikes!), and a digital tachometer which would be much more accurate. You didn't say where the advance mechanism is located in your distributor. From the picture it doesn't appear you can get at it from the top. Is it in the bottom? One tip - The big degree wheel on these distributor machines isn't marked very finely. I made a 30º arc the same diameter as the degree wheel in AutoCad, marked every 1º and mounted it on a thin magnetic sheet. Then I painted a thin black line on the illuminated arrow. I place the little arc on the degree wheel and I can accurately read in 1/2º increments. I've sent you a PM with my phone number if you need more info.
Mike, I think I have found a way around all of this rigamarole that is pretty simple. I found on eBay (item# 170422973205) an inexpensive pulse amplifier that takes the weak distributor magnetic pickup signal and amplifies it until it can be used by my Sun tester. It works for Allen machines too. One can buy a proper Sun amplifier that does exactly the same thing, but they are about 10x more expensive. I do have an adapter plate that lets me mount my Ferrari distributor (boy, those little guys are fat and short) to my Sun machine. The advance mechanism is located in the bottom of my distributor. I think I have to take off the bottom plate and then the mechanism will drop out. When I hold the bottom of the distributor drive shaft and then turn the rotor, the rotor moves like the advance mechanism is in working order, but I want to see how well it advances on my tester. Thanks for the tip about making your own degree arc. Peter, If you got one of these pulse amplifiers, would you no longer have to transfer distributor advance mechanism guts to another distributor in order to test the first distributor? That does seem kinda an involved way of checking out an advance mechanism.....;-) Wil
The CraneCams system uses an infrared light and thus, needs the "black box" to make the signal... which is 12V. At one time, CraneCams did make a 6V system and that would be ideal for the Allen machine, but it has long since been out of production and I've had a hard time finding a NOS/used one on ebay... So, I do the swap. I don't do this often, so it doesn't matter how long it takes (not really that time consuming). Image Unavailable, Please Login Image Unavailable, Please Login
Peter: That schematic you posted sent a thrill up my leg, Chris Matthews style. It's a good thing I had a good buddy who is a tube radio nut. He has over 5000 tubes neatly cataloged in his basement, and easily supplied fresh replacements for me.
Peter, it looks like you have at least one diode tube in the power supply of your machine. Just a thought, but if the diode tube goes bad you can replace the tube with a small solid state diode, much more reliability that way, if originality isn't all number one. Works great on my machine. Wil
Was it you I sent a copy of the Allen manual? The schematic is in the back of it... One of my Dad's friends was (or still is?...) a ham-radio guy and many years ago would build Heath Kits. He had a ton of tubes at one time but at least he still has a tube tester! When I bought my Allen machine, I took it apart (to replace 50+ year old wiring!) and brought my tubes over to him for testing. They still worked! Apparently, tubes are still available (although I think they're mostly of dubious quality now). In any case, I treat this machine gently and let it warm-up first before doing my tests and then let it cool down. And again, I don't run this machine everyday, so it's not being abused. Kinda like the Ferrari...
I can't remember if it was you I got the manual from - I do remember I paid $40 for it, half of what I paid for the Allen! I also cleaned up the wiring and replaced the calibration resistors with pots I mounted on the back of the unit - much easier to get to them. I don't really need the electronics package, I can measure RPM and Dwell externally (the meters are inaccurate anyway) but I do need it to fire the illuminator bulb. As I mentioned previously, when I get to it I plan on converting the unit to 12 V, with a digital tach and a LED illuminator. I do like the drive mechanism in the Allen, with that heavy flywheel /disc and the rubber wheel that in and out radially to adjust the speed. All of the SUNs I have looked at have some kind of composite cone that the drive wheel rides up and down. Most of the cones have several grooves worn into them, and I don't see how they can be smoothly linear when changing speeds.
Do you know who sells those little neon bulbs? One of mine is burnt out. And I think you're mistaken. I do believe it was you I made the copy for, as I did it electronically (scanned each page and emailed it out), but I would have remembered receiving $40 for that! Image Unavailable, Please Login
Mike, My Sun machine doesn't have any grooves worn in the drive cone. The speed change mechanism is just as linear as an Allen machine. Mine has a rubber tire mounted on an aluminum disc, very smooth action. The thing with Sun machines that have messed them up often in the past is that the OPERATOR (good ol' operator error again) doesn't completely disengage the drive mechanism when finished with the machine. This is done by winding the speed knob down all the way until the drive motor disengages from the drive cone. Flat spots in the drive wheel will happen if it isn't disengaged, which starts the destruction process of the drive wheel and drive cone. Wil
You could call Perry Enterprises in Murray, KY (270-759-0661) which was rebuilding Allens a decade ago (I don't know if they are still in business). Or you could try Mouser Part # 36FT050 which was designed for timing lights http://www.mouser.com/ProductDetail/36FT050/?qs=nRZJSAML2huFUD0ZPHFJMg%3d%3d Be sure to wear your safety goggles! And if all else fails, call James Cameron in Hollywood. I hear he has a source for Unobtanium
To get back on-topic, and with a nice solution to the initial problem presented: The very simple solution for running a Marelli--or any--distributor with a magnetic pickup and no amplifier built into the distributor on a Sun (and probably Allen) distributor test machine is to purchase a pulse amplifier for about $30.00 on eBay. No need to alter the internals of your tester machine to adapt to the magnetic pickup distributor. No need to swap ignition advance ass'ys to other test distributors, these work on optical pickups too. Turns out my distributor is working just great, except that the modified ignition installation ends up turning the distributor backwards and the flyweights will only advance 4 degrees, vs. 27 degrees when rotated in the correct direction. So not only was my car severely underjetted, it had no advance to speak of. And a 'professional' mechanic was the one who maintained this car before I owned it. Christ. Wil
Some threads never die. I would just like to say Hi, and thanks for the Allen schematic above. I used it to restore an Allen distributor tester to functionality. I am a EE, and now know quite well how the Allen machine works. Anybody with questions about how to fix one can fire away. I do not have a source for the Neon bulbs, though. Mine work fine. The machine was in a friend's garage. He wanted it gone and I wanted one for my Formula Junior disty. Here are my general recommendations for bringing back an Allen machine that's been sitting around for decades: Check the AC wiring for frayed cords and replace as needed. (In my case, all of it, you can't go wrong there.) Replace *ALL* the electrolytic capacitors, regardless of condition. Close equivalents can be had at any electronics supply or surplus store. In the case of the tachometer, it works on the ratio of two capacitors, so it is possible to replace the 0.5 and 500 uf caps with a .47 and a 470 uf, which are more common. Modern capacitors are so much smaller than the old ones, the new ones can be soldered in attached to the wires and left hanging there. The hard part is checking the tubes. I happen to have a tube tester too, but you won't find one of these in the nearest drug store like when these machines were new! All of the tubes in the Allen are diodes. There are no amplifiers. One of them is a gas discharge tube, which acts like a 105 volt voltage regulator. I needed to replace the full wave bridge rectifier tube (5Y3), but fortunately, these are available from many audiophile sites. The tube in mine was smashed because at some point, the spring that pulls the motor toward the drive wheel broke and hit the tube. Thanks again
That distributor uses a VR or Variable Reluctor. You can feed it into a 4-pin HEI ignition module, ECHTP45 to convert the signal. W = positive lead (+) from the pickup G = negative lead (-) from the pickup C = negative side (-) of the coil B = positive side (+) of the coil Be sure to get the polarity correct. The HEI should trigger on the VR signal negative going zero crossing point. The positive going zero crossing point is not stable enough. Good luck with it.
Did I read correctly that some one has a Allen Distributor Tester manual scanned and email-able? If so would you be willing to send a copy to me?
PM me with your email and I'll send it to you. And follow all of mediasponge's suggestions above, and for gawd sake put a fuse on the power input cord. I can't believe that even back in the 50's they didn't put fuses on these things!
