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Positive ground electical question #1374598 01/23/13 03:49 PM 01/23/13 03:49 PM
Joined: Jan 2003 Posts: 194 Willow Street 4 4spd69gtx OP member
4spd69gtx OP member 4 Joined: Jan 2003 Posts: 194 Willow Street	Im a Firefighter and we have an antique firetruck with 12V positive ground. It is a 1956 Ward LaFrance with a Mopar 392 Hemi of the same vintage. It still has its original ignition system and runs like a dead cat. We are thinking about converting to electronic ignition but with the positive ground we dont know how to approach this.. Suggestions on a new ignition system would be appreciated. Thanks

Re: Positive ground electical question [Re: 4spd69gtx] #1374599 01/23/13 04:23 PM 01/23/13 04:23 PM
Joined: May 2005 Posts: 125 Iowa D dsp member
dsp member D Joined: May 2005 Posts: 125 Iowa	You will have to electrically isolate the ignition module (insulate it from touching any surrounding metal). Connect one side of the ballast resistor supplied with the ignition kit (not the existing one on the truck) to the frame (ground) and the other side to the positive terminal of the ignition coil. The negative terminal of the ignition coil connects to the module as shown in the instructions. The RUN wire from the ignition switch will connect to the body of the ignition module. Mopars have a feature where the ballast resistor is bypassed during cranking. I assume the truck has something similar. This could be accomplished by use of a relay. Connect the START wire to the relay coil (the other side connects to ground) and the wire the NO (normally open) relay contacts in parallel with the ballast resistor.

Re: Positive ground electical question [Re: 4spd69gtx] #1374600 01/23/13 05:04 PM 01/23/13 05:04 PM
Joined: Sep 2009 Posts: 1,805 ky hills thehemikid top fuel
thehemikid top fuel Joined: Sep 2009 Posts: 1,805 ky hills	It would neat to see a pic of the Hemi in there.

Re: Positive ground electical question [Re: 4spd69gtx] #1374601 01/23/13 06:07 PM 01/23/13 06:07 PM
Joined: Aug 2003 Posts: 43,215 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,215 Bend,OR USA	Quote: Im a Firefighter and we have an antique firetruck with 12V positive ground. It is a 1956 Ward LaFrance with a Mopar 392 Hemi of the same vintage. It still has its original ignition system and runs like a dead cat. We are thinking about converting to electronic ignition but with the positive ground we dont know how to approach this.. Suggestions on a new ignition system would be appreciated. Thanks Those trucks should have had a either, depending on which part of the year it was produced, 331 or a 354 C.I. industrial Chrysler motor in them, not a Desoto or Dodge motor. If so it will have 1/2 valve stems, solid liters with adjustable rocker arms, super low compression, a carb. with a built in governor and some other small changes from the car motors Probally around 220 HP, not a hot rod in a heavy truck Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: Positive ground electical question [Re: 4spd69gtx] #1374602 01/23/13 10:20 PM 01/23/13 10:20 PM
Joined: Jun 2008 Posts: 1,822 Colorado D denfireguy top fuel
denfireguy top fuel D Joined: Jun 2008 Posts: 1,822 Colorado	Another approach, maybe more complicated but save some issues in the long run, is to convert it to negative ground. The things polarity sensitive would be the generator/regulator, the radio (two way and AM if it had one), and the starter/solenoid. Lights do not care, the Federal Q will run backwards but it would sound the same as frontwards and the revolving lights may have to be changed. Craig 2014 Ram 1500 Laramie, 73 Cuda Previous mopars: 62 Valiant, 65 Fury III, 68 Fury III, 72 Satellite, 74 Satellite, 89 Acclaim, 98 Caravan, 2003 Durango Only previous Non-Mopar: Schwinn Tornado

Re: Positive ground electical question [Re: denfireguy] #1374603 01/23/13 10:42 PM 01/23/13 10:42 PM
Joined: Jan 2004 Posts: 27,347 Today? Who Knows? 1_WILD_RT Management Trainee
1_WILD_RT Management Trainee Joined: Jan 2004 Posts: 27,347 Today? Who Knows?	Quote: Another approach, maybe more complicated but save some issues in the long run, is to convert it to negative ground. The things polarity sensitive would be the generator/regulator, the radio (two way and AM if it had one), and the starter/solenoid. Lights do not care, the Federal Q will run backwards but it would sound the same as frontwards and the revolving lights may have to be changed. Craig Generator will go both ways, thats why you need to polarize it.. If it has a two way it' probably a Motorola & if thats the case it's probably built as a negative ground & the mount is isolated.... Starter & solenoid don't care unless there a clamping diode & since clamping diodes didn't show up till the 80's......... "The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."

Re: Positive ground electical question [Re: 1_WILD_RT] #1374604 01/23/13 11:06 PM 01/23/13 11:06 PM
Joined: May 2003 Posts: 2,414 St. Croix, US Virgin Islands D David_in_St_Croi top fuel
David_in_St_Croi top fuel D Joined: May 2003 Posts: 2,414 St. Croix, US Virgin Islands	At least Pertronix makes both positive and negative ground ignition modules to replace the points and condensers. Might see if they have one for a V8. Otherwise as mentioned just convert it. We converted our 63 MG Midget when we put a Pertronix in it, quite straightforward. Otherwise just give it a good tune up as negative or positive ground shouldn't make a difference to the points and condenser, and that is all that is changed in the most basic electronic ignition conversions. https://www.facebook.com/THENEWCDRA Proud member of the liberal scientific elite

Re: Positive ground electical question [Re: 1_WILD_RT] #1374605 01/24/13 12:17 AM 01/24/13 12:17 AM
Joined: Jun 2008 Posts: 1,822 Colorado D denfireguy top fuel
denfireguy top fuel D Joined: Jun 2008 Posts: 1,822 Colorado	Quote: Quote: Another approach, maybe more complicated but save some issues in the long run, is to convert it to negative ground. The things polarity sensitive would be the generator/regulator, the radio (two way and AM if it had one), and the starter/solenoid. Lights do not care, the Federal Q will run backwards but it would sound the same as frontwards and the revolving lights may have to be changed. Craig Older Motorolas had polarity plugs. That was easier than dealing with how to ground the antenna and coax without shorting out the radio. Generator will go both ways, thats why you need to polarize it.. If it has a two way it' probably a Motorola & if thats the case it's probably built as a negative ground & the mount is isolated.... Starter & solenoid don't care unless there a clamping diode & since clamping diodes didn't show up till the 80's......... 2014 Ram 1500 Laramie, 73 Cuda Previous mopars: 62 Valiant, 65 Fury III, 68 Fury III, 72 Satellite, 74 Satellite, 89 Acclaim, 98 Caravan, 2003 Durango Only previous Non-Mopar: Schwinn Tornado

Re: Positive ground electical question [Re: 1_WILD_RT] #1374606 01/27/13 02:22 PM 01/27/13 02:22 PM
Joined: Oct 2010 Posts: 606 Montana Y Yancy Derringer mopar
Yancy Derringer mopar Y Joined: Oct 2010 Posts: 606 Montana	Quote: Quote: .............. convert it to negative ground. The things polarity sensitive would be the generator/regulator, the radio (two way and AM if it had one), and the starter/solenoid. Lights do not care, the Federal Q will run backwards but it would sound the same as frontwards and the revolving lights may have to be changed. Craig Generator will go both ways, thats why you need to polarize it.. If it has a two way it' probably a Motorola & if thats the case it's probably built as a negative ground & the mount is isolated.... Starter & solenoid don't care unless there a clamping diode & since clamping diodes didn't show up till the 80's......... The last is largely correct Lights, solenoids, motors "don't care." Anything you have that's electronic WILL. The caveat to re--polarizing the generator is the CONTACTS IN THE REGULATOR. Some regulators (replacement aftermarket) are designed for either polarity to reduce inventory. Some OEM regulators were built with different contact materials, and would burn out if reversed. If you have a positive ground alternator, that will have to be reworked/ replaced, depending. The thing is, I'm old enough to have "been there." I've ridden in, driven, tuned up, been around cars for a very long time, and back then ALL of them had breaker points ignition. I'm sure you don't drive that thing very far, are you REALLY going to gain anything? There is no reason on earth that a PROPERLY gone through distributor won't work just fine with breaker points. How often is the truck run?

Re: Positive ground electical question [Re: Yancy Derringer] #1374607 01/27/13 02:42 PM 01/27/13 02:42 PM
Joined: Sep 2005 Posts: 12,481 Chino Valley RodStRace I Live Here
RodStRace I Live Here Joined: Sep 2005 Posts: 12,481 Chino Valley	For a low use vehicle, keep it stock and fix it right. That way, 10 years from now the next guy can refer to factory stuff to fix it, not have to figure out what you did... For more on changing polarity, http://mopar.pairserver.com/p15d24ph_forum/index.php?/page/p15d24/tech/tech_tips.html drop to Convert Or Keep The Faith, 6 or 12 volts

Re: Positive ground electical question [Re: RodStRace] #1374608 02/02/13 09:03 AM 02/02/13 09:03 AM
Joined: Jan 2003 Posts: 194 Willow Street 4 4spd69gtx OP member
4spd69gtx OP member 4 Joined: Jan 2003 Posts: 194 Willow Street	Ok guys, heres the thing. This truck is run only a few times a year. It is not in service and therefore has no radio to worry about or any electronics. Thinking about the electronic ignition route so we dont have to worry about dealing with the points and condenser at all. We had it out on a funeral detail recently and quite honestly all it did was pop and spit the whole time. If we were lucky it was firing on 5 or 6 cylinders the whole time. Really looking more for recomendations on where to get positive ground electronic ignition converstion kits

Re: Positive ground electical question [Re: 4spd69gtx] #1374609 02/02/13 02:56 PM 02/02/13 02:56 PM
Joined: Jan 2004 Posts: 27,347 Today? Who Knows? 1_WILD_RT Management Trainee
1_WILD_RT Management Trainee Joined: Jan 2004 Posts: 27,347 Today? Who Knows?	Is there still an ID tag on the distributor? If you can get that info Petronix offers conversions & complete new distributors for quite a few applications including positive ground stuff... Full catalog http://www.pertronix.com/catalogs/pdf/ptx/2012/Pertronix2012.pdf "The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."

Re: Positive ground electical question [Re: 4spd69gtx] #1374610 02/02/13 03:26 PM 02/02/13 03:26 PM
Joined: Aug 2003 Posts: 43,215 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,215 Bend,OR USA	Two things come to mind, bad gas and fouled spark plugs will make a motor run bad On the gas I use avaition 100 LL in any of my cars that don't get driven a lot due to its shelf life of 18 months before starting to go bad Most of the pump gas made today has a shelf life of 90 days or less One of my custmers has a 1968 Hemi Charger that is a god weather only car so it gets parked up here for around 7 months between uses, he had a starting problem on it after it sat for four months , most pump fuel looses its octane after sixty days, that some avaition 100 LL fixed He now puts in 10 to 15 gallons of 100 LL at the end of summer before parking the car for the winter, his fuel cell is 34 gallons Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

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