coil polarity 1928 phaeton

[wbs]

hello- i guess the coil is original-so how can i tell if my coil is a straight or slanted ? catalogs of parts don't seem to show the different types. also in determining driver or passenger side , i guess it is meant with the terminals pointing to the road not the sky--my car came with terminals pointing up-people says polarity makes a difference in the spark in the plug--thank you

[burner31]

The positive will go to your ignition switch, the negative will go to your junction box and end up at your relay.
If I'm not mistaken.
Anybody...correct me if I'm wrong here.

[burner31]

Coil points down

[2manycars]

A slant pole coil has the small terminals mounted slanting away from the center high tension terminal. If your coil is original to the car, it will likely be a slant pole. Straight pole coils came later, and all 3 terminals are in line with the length of the coil Original coils have the mounting bracket welded to the coil can. Replacements have a clamp on bracket. Replacement coils will be marked + and - or dist and bat. Originals do not have markings.

[Tom Wesenberg]

Lots of good information if you do a Google search for "coil polarity" and read what the chicagolandmgclub has to say. This will be the first or second listing in the Google search.

[Mitch//pa]

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[Patrick L.]

Coil polarity should be the same as the battery. If there are no coil markings, then, the pencil test or one of the coil polarity thingys need to be used.

A coil will still work if the polarity is incorrect, but, at a 20-30% reduction.

If the coil is pointed 'skyward' then it may be filled with oil which means it won't work well if tipped over and is pointed ' groundward'.

[Bruce of MN]

I did the voltmeter test in the MG club article and with the meter in the 1000 v range, it barely pulsed positive. I have a Bratton's coil and it is hooked up properly, but I wanted to try the test.

[wbs]

thanks to all who replied - my coil has the mounting bracket welded to the coil can not a clamp-on bracket and has no markings but all 3 terminals are in line with the length of the coil -hence the conflict betweenn old and new--i had read the post on polarity prior to submitting this post but was afraid to use my volt meter because the ac max on it is 750v and dc max is 50 v. and i was afraid of ruining it

[Tom Wesenberg]

Original coils have the brackets spot welded in place.
Can you post a picture of your coil?

Slant pole coils have the two outside terminals slanting outward in a / \ style. If you have a slant pole coil, be sure the first thing on the terminals is an insulating washer. Then you have the flat washer, lock washer, and hex nut. Then the wire terminal and barrel nut finishes the installation.

I was just looking in my July 1, 1931 Parts Price List book, and I see the coil is listed as A-12000. I would think it should have a "B" suffix since it has a second design (straight pole vs. slant pole).

[wbs]

thank you mr wesenberg- i will try to get my wife to take pix of coil when she gets home weds.- i may make a sketch of coil before weds

[katy]

Remove the coil and shake it. If it's oil filled you will hear oil sloshing around inside it and it should be mounted with the terminals on top. If it's not oil filled the proper orientation for a Model A coil is with the terminals on the bottom.

[wbs]

thanks again to all replied- i've followed everyone's advice and to mr wesenberg's expert advice, on closer examination , the primary winding terminals are angled out exactly as he said-i have not had a chance to do the shake test for oil yet as it is too late in the day, but will do so tues. thanks again

[Tom Wesenberg]

You won't have to do the shake test, since you have a slant pole, it's likely an original coil.
Look carefully on the flat side on the mounting bracket, and you should find a date code.

[wbs]

from previous messages:" slant pole coil has the + on the driver's side (left)of coil"--A's had pos. ground. so the points [ground ] side via ignition switch by way of red wire goes to driver side --the black wire from neg battery/starter via ammeter terminal goes to passenger side------correct?

[Mitch//pa]

Originally Posted by 1930 coupe

There are so many variables in coils and wiring in cars that it makes it very difficult to know if your polarity is correct. About the only easy way to know if your polarity is correct is to get a polarity tester, about all the vendors sell them.

Agree all we can do is suggest. I have gotten incorrect results from the other method.

[BILL WILLIAMSON]

If all else fails, try it BOTH ways & see which way makes it run BETTER.
Guess Who?