Ignition Polarity

This Forum is dedicated to the Hobbyist I.C. (Internal Combustion) Engine Community.

Moderators: Harold_V, JackF

hammermill
Posts: 2938
Joined: Sun Jun 27, 2010 10:43 pm
Location: pendleton or

Re: Ignition Polarity

Post by hammermill » Tue Feb 03, 2015 10:17 pm

Indeed thanks!

golfpin

Re: Ignition Polarity

Post by golfpin » Fri Feb 06, 2015 7:49 am

Thanks Ken,
can,t help but then ask the question, before the universal use of the alternator ie when generators were used, many cars were positive earth [ground] pre about 1960. Wonder how this reflects on the negative earth treatise. Always curious, anybody out there care to comment.
Cheers Golfpin.

tornitore45
Posts: 1417
Joined: Tue Apr 18, 2006 12:24 am
Location: USA Texas, Austin

Re: Ignition Polarity

Post by tornitore45 » Fri Feb 06, 2015 8:01 am

With positive ground system the coil was internally connected with the primary reversed. Actually switching the low voltage terminals on any coil changes the polarity of the spark. There is a conceptual difference but in practice has no effect, as long as the spark is negative.
Mauro Gaetano
in Austin TX

User avatar
ken572
Posts: 2600
Joined: Sun Mar 14, 2010 8:11 pm
Location: Mesa, Arizona. 85201-1517

Re: Ignition Polarity

Post by ken572 » Fri Feb 06, 2015 2:12 pm

golfpin wrote:Thanks Ken,
can,t help but then ask the question, before the universal use of the alternator ie when generators were used, many cars were positive earth [ground] pre about 1960. Wonder how this reflects on the negative earth treatise. Always curious, anybody out there care to comment.
Cheers Golfpin.
Good Morning :!: golfpin :D

The only positive ground system I recall was a (BLUNDER) that
Ford made in (1955 ONLY) :roll: and was the joke of the industry.
They didn't start well in the cold weather and and many people blew
up battery's jump starting other cars, because they didn't check to make
sure they had the cable's flipped around. Fords Better Idea :lol:
sure wasn't that one.. :lol: :lol:

Edit/Add To:
I forgot to mention, that 1955 was the first
year for 12 volt systems to be used in Fords.
12 volt system was a good idea.. :D

Ken.
One must remember.
The best learning experiences come
from working with the older Masters.
Ken.

dly31
Posts: 1042
Joined: Sun Jun 27, 2004 11:29 pm
Location: Northeast Alabama

Re: Ignition Polarity

Post by dly31 » Fri Feb 06, 2015 11:28 pm

I seem to remember that all 6 volt Fords were positive ground. GM (Delco Remy) were all negative ground and I think Mopar (Autolite) were also. Many, if not all, of the British cars, motorcycles, and tractors (Lucas) were positive ground up as long as they used generators.
Don Young

golfpin

Re: Ignition Polarity

Post by golfpin » Mon Feb 09, 2015 10:04 am

Interesting all points, seem to remember as an apprentice was told that one of the reasons for the move to neg ground was because of the massive build up of corrosion that occurred around the one poles [can,t remember which, but sounds old wives tale] how ever do recall that chrysler were one of the first if not the first to start using Alternators [1960?] and that in order to use an alternator you had to have neg ground..... I am on thin ground here perhaps some of our very "enlightened" contributors can comment on this. Most of the Brit stuff at this time was pos earth also was Peugeot French! comments !!!
Golfpin

User avatar
ken572
Posts: 2600
Joined: Sun Mar 14, 2010 8:11 pm
Location: Mesa, Arizona. 85201-1517

Re: Ignition Polarity

Post by ken572 » Mon Feb 09, 2015 2:03 pm

golfpin wrote:Interesting all points, seem to remember as an apprentice was told that one of the reasons for the move to neg ground was because of the massive build up of corrosion that occurred around the one poles [can,t remember which, but sounds old wives tale] how ever do recall that chrysler were one of the first if not the first to start using Alternators [1960?] and that in order to use an alternator you had to have neg ground..... I am on thin ground here perhaps some of our very "enlightened" contributors can comment on this. Most of the Brit stuff at this time was pos earth also was Peugeot French! comments !!!
Golfpin
Good Morning :!: Golfpin :D
Back in the day I purchased from the original owner,
a 1960 Chrysler Imperial Lebaron (Factory Built at Chrysler)
(20" Stretch Limo) and it had a generator and a 12 Volt NEG
Ground Electrical System.

Ken. :)
One must remember.
The best learning experiences come
from working with the older Masters.
Ken.

tornitore45
Posts: 1417
Joined: Tue Apr 18, 2006 12:24 am
Location: USA Texas, Austin

Re: Ignition Polarity

Post by tornitore45 » Mon Feb 09, 2015 2:53 pm

Back in the 60 when car alternator saw the light of day, standard high current silicon rectifiers had the cathode connected with the stud. The stud must mount on a heatsink. That would make a Positive Ground design much easier, no isolation between the diode and the heatsink and the heatsink in contact with the chassis.

The switch from positive to negative ground must have been motivated by some other reason.

For corrosion you want the wiring negative and the chassis positive like all Telephone Switching Office.
When telephone used fine wire relays it made sense; you rather have corrosion of the sturdy chassis than a hair size wire. Today there are fewer relay in a central office.
Mauro Gaetano
in Austin TX

User avatar
Lew Hartswick
Posts: 712
Joined: Sat Jan 04, 2003 10:45 am
Location: Albuquerque NM

Re: Ignition Polarity

Post by Lew Hartswick » Mon Feb 09, 2015 11:13 pm

dly31 wrote:I think polarity has something to do with the ionizing of the fuel mixture but am not sure. .
I think ( I am remembering from a LOOOOONG time ago) it had to do with center electrode eroding worse
with one of the polarities.
...lew...

golfpin

Re: Ignition Polarity

Post by golfpin » Tue Feb 10, 2015 12:30 am

Informative replies chaps especially that from Mauro, seems you are vastly more read on electrics[tronics] and so well put ..wonder what the influence/requirement was that pushed the designers to neg ground come on must be some one out there with a B Sc. in electronics that can give an answer!
Maybe that corrosion around the pole was not such an old wives tale after all.
Thanks Golfpin

golfpin

Re: Ignition Polarity

Post by golfpin » Tue Feb 10, 2015 7:24 am

Further to curiosities in electrics, I recall reading that in the development stages of the Pratt and Whitney engine, that was to power the P 47 Thunderbolt, problems emerged at high altitude, and that the ignition systems were "pressurized" to overcome what ever the problem was, very vague on this one but electrics to me are vague anyway. Just know that it can,t be readily seen and it does bite.....anyone care to add to this tit bit?
Cheers Golfpin

User avatar
ronm
Posts: 765
Joined: Sun Jan 05, 2003 9:32 am
Location: Colorado

Re: Ignition Polarity

Post by ronm » Tue Feb 10, 2015 9:46 am

Up until at least the 80's, Mack trucks that were specified as water trucks-i.e. had a tank of some sort mounted on them, were 12V POSITIVE ground. Supposed to reduce corrosion...don't know if it worked or not, but Mack knew a lot about building trucks. I ran into this when hooking up a 2-way (not CB) radio in an oilfield truck.

Post Reply