frd1419 Posted June 17, 2009 Share Posted June 17, 2009 Anyone know what the coil output is in the six volt system? I have had trouble starting my truck. I checked the spark output with a kv tester and found the col is putting out 6kv and I have 4kv at the plugs. Seems to low to me. When I remove the coil wire from the cap and hold it close to ground I get 15kv. ???? Quote Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/ Share on other sites More sharing options...
Rob Posted June 17, 2009 Share Posted June 17, 2009 Anyone know what the coil output is in the six volt system? I have had trouble starting my truck. I checked the spark output with a kv tester and found the col is putting out 6kv and I have 4kv at the plugs. Seems to low to me. When I remove the coil wire from the cap and hold it close to ground I get 15kv. ????That is not too far off if I remember correctly. A coil is an oil filled transformer and the breaker points "chop" the incomming and rising DC voltage that is fed to the primary winding. This action induces a voltage across the secondary winding via magnetic induction. There are many more turns of wire in the secondary side of the coil than the primary winding and this action steps up the voltage output at the coil. This high voltage is then distributed via the distributor, rotor, cap, and wires to the appropriate spark plug.You are stepping up somewhat less than six vdc up to operating voltage to fire the spark plugs. You could substitute for a short while a 12 battery and see if the engine starts better but this is only for testing. If the coil is making 15kv, (open circuit) it sounds as if you have an ignition timing issue to evaluate. The ignition spark must occut at the appropriate time for the engine to fire easily if the problem is ignition related. I seem to remember this situation a short while ago.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-36819 Share on other sites More sharing options...
HK Trucking Posted June 17, 2009 Share Posted June 17, 2009 I remember "back in the day" that some guys would substitute an 8 volt battery in those old 6 volt systems to cure hard starting problems.Those 8 volt batteries looked weird in the old "exposed cell connector" format, and they had 4 vent caps. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-36821 Share on other sites More sharing options...
Greg Rider Posted June 18, 2009 Share Posted June 18, 2009 Also double check the points gap. Look to see if they are a little burnt. New ones are cheap. If they are outta whack the rise time in the coil will be incorrect resulting in a weak spark. Weren't you having concerns with this distributor? This is one of the MANY reasons that I went to 12 volts. Quote #1 on A-model registryIf I drink because of work, why can't I drink at work? Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-36907 Share on other sites More sharing options...
frd1419 Posted June 21, 2009 Author Share Posted June 21, 2009 I found out the distributor is correct. I changed the cap, rotor, points and condensor.I now l get 9 kv at the coil but no plug readings, if I pull a plug and lay it on the manifold I see a spark. I touch the kv probe there and get 15kv at the tip, but no readings at the plug wires. Any ideas? Quote Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-36989 Share on other sites More sharing options...
Rob Posted June 22, 2009 Share Posted June 22, 2009 I found out the distributor is correct. I changed the cap, rotor, points and condensor.I now l get 9 kv at the coil but no plug readings, if I pull a plug and lay it on the manifold I see a spark. I touch the kv probe there and get 15kv at the tip, but no readings at the plug wires. Any ideas?You probably have resistive plug wires. Get a set of solid core type wires. With your truck I highly doubt you are concerned with radio interference which is what resistive plug wires were engineered to combat. They cause a lot of voltage drop through them.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37043 Share on other sites More sharing options...
frd1419 Posted June 24, 2009 Author Share Posted June 24, 2009 More information: When I keep the spark plug 1/4" away from the block I measure 8kv on the spark plug wire and can see the better spark arching. When I put it down on the block weak spark that does not even register on the kv tester. ??????? Quote Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37138 Share on other sites More sharing options...
Rob Posted June 24, 2009 Share Posted June 24, 2009 More information: When I keep the spark plug 1/4" away from the block I measure 8kv on the spark plug wire and can see the better spark arching. When I put it down on the block weak spark that does not even register on the kv tester. ??????? It has to do with rise and decay time of the RC network you have set up. I don't expect you to be able to analyze that statement but it should suffice to say that the closer you place the spark plug lead to a ground, (block in this case) the spark has less resistance through the medium of the surrounding air and jumps more readily. This occurs earlier in the field strength of the rise time of the output pulse of the transformer, (coil). When you increase the distance from lead to ground, the arc is not strong enough to jump the air gap until the rise of the pulse is such that the secondary of the coil reaches/nears saturation level. Upon saturation, the coil cannot increase voltage further. Saturation levels change in transformers as they age.If it were me, I'd get a new coil using external resistance for use with an external ballast resistor to rule out that component.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37144 Share on other sites More sharing options...
frd1419 Posted June 25, 2009 Author Share Posted June 25, 2009 I have tried a new coil with the same results. As far as I know I do not think ms 6 volt system uses a ballast resistor. Quote Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37177 Share on other sites More sharing options...
Rob Posted June 25, 2009 Share Posted June 25, 2009 I have tried a new coil with the same results. As far as I know I do not think ms 6 volt system uses a ballast resistor.It should whether it be an actual ballast resistor, or a primary resistance wire. On the coil small terminals are there two wires on one terminal, and one on the other leading to the breaker points? External resistance is not used during the crank cycle as the resistance is by-passed with the ignition switch applying full available battery voltage to the primary side of the coil during engine cranking. When you either let off of the key, or button that causes the engine to crank, the primary resistance is switched back into the circuit. This allows the breaker points to have an acceptable service life. Without this resistance, the point life would be remarkably short due to the higher voltage they are switching on and off. Connect a basic voltmeter to the battery with no accessories on for a baseline measurement. Then connect the voltmeter to the potential side of the coil small terminal, and the other to a good ground. Pull the "trigger wire" from the starter solenoid, and with the ignition switch "on" and not cranking the engine when the starter switch is engaged, you should have very close to the battery voltage available at this terminal. If you do not, you have a bad, or high resistance circuit impeding current flow. Run a wire directly from the battery to the coil and then crank the engine. If it starts readily, isolate your wiring, or ignition switch problem. When you disengage the starter switch there should be about 80% of available system voltage to the breaker points during normal operation due to this primary resistance being switched in.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37178 Share on other sites More sharing options...
theakerstwo Posted June 25, 2009 Share Posted June 25, 2009 What Rob said. I could have told you that but it would not came out like that in fact i would have got you messed up big time cause i could not have decribed that to anyone. But hes right. If you get shocked by a coil then dont leave any gap between you and the wire. Just grab it and hold on. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37180 Share on other sites More sharing options...
HK Trucking Posted June 25, 2009 Share Posted June 25, 2009 I don't think they used resistors on 6 volt systems.To my knowledge, resistors were introduced when 12 volt systems came on the scene in order to cut the primary voltage back to about 8 volts to prevent burning of the points. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37195 Share on other sites More sharing options...
Rob Posted June 25, 2009 Share Posted June 25, 2009 I don't think they used resistors on 6 volt systems.To my knowledge, resistors were introduced when 12 volt systems came on the scene in order to cut the primary voltage back to about 8 volts to prevent burning of the points.Hi Herb, both of my six volt systems use external ballast and cut the operating voltage back to about 4.75 volts.Sheila, (51 Mack) has a light bulb installed into a heat sink for this purpose.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37197 Share on other sites More sharing options...
frd1419 Posted June 25, 2009 Author Share Posted June 25, 2009 My system looks simple or so I thought. I only have one wire powering the coil and the other side to the distributor. The power to the coil comes from a simple push/pull switch on thje dash. The starter has a push button switch above the gas pedal to start. Quote Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37200 Share on other sites More sharing options...
Rob Posted June 25, 2009 Share Posted June 25, 2009 My system looks simple or so I thought. I only have one wire powering the coil and the other side to the distributor. The power to the coil comes from a simple push/pull switch on thje dash. The starter has a push button switch above the gas pedal to start.With only a single wire on the two small terminals of the coil, you do not have primary resistance in that circuit.I would try to extra voltage that either an 8VDC cell offers, or a 12VDC to see if the engine fires more readily.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37205 Share on other sites More sharing options...
mackmixer Posted June 25, 2009 Share Posted June 25, 2009 Make sure that your new rotor button is not leaking secondary voltage (high) through the button and grounding to the top of the distributor shaft. You can check this easily by removing the distributor cap and taking the coil wire out of the center of the cap and put it on top of the rotor button to see if it discharges through the new rotor button while turning the engine over with the coil.If it does then your new rotor button is leaking high voltage through to the distributor shaft and you won't get good spark through the button to the spark plugs. Quote David Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37206 Share on other sites More sharing options...
frd1419 Posted June 25, 2009 Author Share Posted June 25, 2009 (edited) I have tried that and no voltage is leaking through. Could the modern parts be to efficient for the older ignition systems? Edited June 25, 2009 by frd1419 Quote Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37213 Share on other sites More sharing options...
engine2quarters Posted June 27, 2009 Share Posted June 27, 2009 Hi Fred. Still at it, huh?I run solid metal core plug wires, and solid core coil to distributor. Resistorized wire hadn't been invented in the 40's, I don't think.Spark plugs are Champion D14, I think, and are non-resistorized, gapped per the Motor's manual. I have no ballast resistors anywhere. The original 'town' did install a bypass capacitor from the terminal on the coil to surpress electrical noise for their 'town' FD radio, which I removed the leads to.I run a large (physical size) 6 volt battery, that cranks my EN330 over quite quickly for being almost 10 years old, in the dead of winter. IT only sees a charger 1 or 2x a year.I'm running the short coil, about 3 inch high, which I believe is original. I can't remember how many terminals on the coil, I think one. It has the 6 v (neg) from the starter solenoid, a lead to the distributor, and one to the dash electronic tach. It should show in one of the pics I sent you.If voltage is missing someplace, sound like a high resistance. Quote Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37267 Share on other sites More sharing options...
frd1419 Posted June 28, 2009 Author Share Posted June 28, 2009 Still at it. I measured the ohms of my wires and I get 5,000 ohms, but I had it running on theses wires before . Now while testing it today I stopped getting readings from the coil while it is attached to the cap. when I pull that off and ground it I get good spark and get 30kv. Looks like what ever is causing my spark loss is getting worse . Quote Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37339 Share on other sites More sharing options...
Greg Rider Posted June 28, 2009 Share Posted June 28, 2009 This may sound stupid but I would put all of the old ignition parts back on . Then one at a time switch things and re-test. It is difficult to diagnose this on a 'puter without seeing. Also if it makes a hill of crap or not my plugs are Champion D21. Parts guys laugh when I ask about platinum tips!! Quote #1 on A-model registryIf I drink because of work, why can't I drink at work? Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37348 Share on other sites More sharing options...
Mike Posted June 29, 2009 Share Posted June 29, 2009 This may sound stupid but I would put all of the old ignition parts back on . Then one at a time switch things and re-test. It is difficult to diagnose this on a 'puter without seeing. Also if it makes a hill of crap or not my plugs are Champion D21. Parts guys laugh when I ask about platinum tips!! Although that sounds good Greg, if he would just give the truck to one of us, sign the title over, his worries would be less than before. Sounds like a good solution to the problem. mike Quote Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37373 Share on other sites More sharing options...
Greg Rider Posted June 29, 2009 Share Posted June 29, 2009 Although that sounds good Greg, if he would just give the truck to one of us, sign the title over, his worries would be less than before. Sounds like a good solution to the problem. mike I bet that I'm closer to Long Island than you!!!!!!!! Quote #1 on A-model registryIf I drink because of work, why can't I drink at work? Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37392 Share on other sites More sharing options...
Mike Posted June 30, 2009 Share Posted June 30, 2009 I bet that I'm closer to Long Island than you!!!!!!!! Your right, I bet I can get into my PIPER Arrow and be their in a couple of hrs.......or I can make a phone call and a friend with a Falcon 20 can fix me right up at KJWN. I still have my clothes on as we speak. HA HA HAYe Haw!!!!mike Quote Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37396 Share on other sites More sharing options...
Rob Posted June 30, 2009 Share Posted June 30, 2009 Your right, I bet I can get into my PIPER Arrow and be their in a couple of hrs.......or I can make a phone call and a friend with a Falcon 20 can fix me right up at KJWN. I still have my clothes on as we speak. HA HA HAYe Haw!!!!mikeYeah, well Scotty is readying the transporter room as we speak for me.If I knew the owners phone number I would just fax my ass over there, (even though it may take a few scans to fit).Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37397 Share on other sites More sharing options...
Mike Posted June 30, 2009 Share Posted June 30, 2009 Yeah, well Scotty is readying the transporter room as we speak for me.If I knew the owners phone number I would just fax my ass over there, (even though it may take a few scans to fit).RobPoor Fax Machine may not last long due to high stress load. mike Quote Link to comment https://www.bigmacktrucks.com/topic/9759-6-volt-coil-output/#findComment-37411 Share on other sites More sharing options...
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