Wiring
Hotshot
Joined: Feb 2015
Posts: 17,559
Likes: 1,081
From: Central Delaware
The coils were marked the same, + and -. They were not marked as either side being the ground.
Logistics Pro
Joined: Sep 2014
Posts: 4,920
Likes: 21
From: Bothell & Silverdale, WA
I think you will find that it doesn't really matter because the primary windings of the coil are isolated from everything. There used to be talk that metal would transfer on the point contacts to the electrode side if the polarity was reversed on the coil, which is true. However, with the correct polarity, metal would transfer to the anode side of the contact points. You get to pick your poison - which side of the points do you want to file?
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Maybe, but were they marked differently pre-56?
I heard it will affect the plugs. Easy enough to check:
http://mgaguru.com/mgtech/ignition/ig104.htm
"Why then do we worry about coil polarity? Because the spark plugs do care which way the electrons are flowing in the high tension circuit. The spark plug has a thermally insulated center electrode (surrounded by ceramic). With engine running the center electrode runs substantially hotter than the exposed end electrode. Design of the ceramic insulator determines how hot the center electrode will run, leading to the designation of hotter or colder spark plugs. As electrons go, they love to jump away from a hot surface and fly toward a colder surface, so it is easier to drive them from hot to cold rather than from cold to hot. End result is a difference of 15 to 30 percent in voltage required to make spark "initially" jump the gap on the plug depending on which way it is going."
I heard it will affect the plugs. Easy enough to check:
http://mgaguru.com/mgtech/ignition/ig104.htm
"Why then do we worry about coil polarity? Because the spark plugs do care which way the electrons are flowing in the high tension circuit. The spark plug has a thermally insulated center electrode (surrounded by ceramic). With engine running the center electrode runs substantially hotter than the exposed end electrode. Design of the ceramic insulator determines how hot the center electrode will run, leading to the designation of hotter or colder spark plugs. As electrons go, they love to jump away from a hot surface and fly toward a colder surface, so it is easier to drive them from hot to cold rather than from cold to hot. End result is a difference of 15 to 30 percent in voltage required to make spark "initially" jump the gap on the plug depending on which way it is going."
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Logistics Pro
Joined: Sep 2014
Posts: 4,920
Likes: 21
From: Bothell & Silverdale, WA
Maybe, but were they marked differently pre-56?
I heard it will affect the plugs. Easy enough to check:
Ignition coil polarity
"Why then do we worry about coil polarity? Because the spark plugs do care which way the electrons are flowing in the high tension circuit. The spark plug has a thermally insulated center electrode (surrounded by ceramic). With engine running the center electrode runs substantially hotter than the exposed end electrode. Design of the ceramic insulator determines how hot the center electrode will run, leading to the designation of hotter or colder spark plugs. As electrons go, they love to jump away from a hot surface and fly toward a colder surface, so it is easier to drive them from hot to cold rather than from cold to hot. End result is a difference of 15 to 30 percent in voltage required to make spark "initially" jump the gap on the plug depending on which way it is going."
I heard it will affect the plugs. Easy enough to check:
Ignition coil polarity
"Why then do we worry about coil polarity? Because the spark plugs do care which way the electrons are flowing in the high tension circuit. The spark plug has a thermally insulated center electrode (surrounded by ceramic). With engine running the center electrode runs substantially hotter than the exposed end electrode. Design of the ceramic insulator determines how hot the center electrode will run, leading to the designation of hotter or colder spark plugs. As electrons go, they love to jump away from a hot surface and fly toward a colder surface, so it is easier to drive them from hot to cold rather than from cold to hot. End result is a difference of 15 to 30 percent in voltage required to make spark "initially" jump the gap on the plug depending on which way it is going."
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Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Naturally just had to check the coil in the slick last night. All is right with the universe, ha ha. The pencil trick sounds a little sketchy to me in terms of getting zapped, so used analog voltmeter connected as shown between the high tension lead in the coil, and ground. The takeaway is to disregard whatever markings are on the coil (if necessary) to get it right - look for an upward swing in the needle on the voltmeter, if you don't get this the coil is hooked up wrong no matter what the terminals are marked.
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