Reversed polarity on ignition coil

[HappyJack]

Hi folks,

It’s been a while since I posted — Abby was down awaiting new gas tank, fuel pump, oil pump, blue coil  and a few other odds and ends, including a Hoover Bit on the oil cooler tin.  As it turned out, the fuel tank filler neck was too long to fit into the MIGI — should have looked at the forum first and I would have found out that the neck needed to be cut and re-

welded — oh well.  1st guy I took it to wanted a minimum of 2 hours @ $ 80/hr but estimated somewhere between two and three hours to get the job done.  Needless to say, I thought about it for a day, retrieved the tank and found another welder — he wanted $ 20 to do the job, but it took him 2 weeks (due to illness) to get the tank done.

Once I got the tank in (old one was REALLY rusted and was causing the fuel filter to clog & stall the engine) and since the car was down for a while, I decided to also change out the fuel pump and since the car was running with low oil pressure at idle (red light blinking more than it should) and running hot at speed, I also changed out the oil pump with a 26mm pump.  And since I had the engine pulley off I also installed an aluminum, etched after market pulley.

The last thing I did today was install a new Bosch Blue Coil.  Found out that the old black coil was installed with the polarity reversed — I swapped the wires around and made sure that plus went to the positive terminal and minus to the negative terminal.  Then came the test drive.

The car idles well, accelerates well and runs very well and very smoothly at speed.  What a difference!! My only problem now is answering the question as to which “part change out” caused the great improvement – although I guess it does not really matter.  But it does make me wish that I had followed suggestions to change one thing at a time and then test drive…!!!

— now it’s on to  changing out the distributor for an Aircooled.net SVD distributor with electronic ignition…got to get ready for the VA Beach Car Show later this month.  I’ll let you know if changing out the distributor makes a difference in the drivability and performance of this car. (right not I’m running with a stock Vac Advance dist. on loan from Royal).

Then I’ll have to decide if I want to go down the path that others  did in changing out the front brakes for disk brakes.  

By the way, I sat down the other day and made a list of all the new parts I put on this car — but did not add prices to the list — I did not want to know…!!!

Anyone have any experience with reversed polarity on the ignition coil?  Could that have led to a poorly-running engine?

Thanks,  Jack

[newkitman]

Jack,

Check out a How To Keep Your VW Alive book. I believe Mr. Muir gives a small account of what happens when the polarity is reversed.

Allen Caron
VW based 53MGTD - "MoneyPenny"
"If one thing matters, everything matters" - from the book The Shack

[edward ericson]

Awesome, Jack. Look forward to meeting you in VA beach.

[Royal]

Spark polarity:

http://mgaguru.com/mgtech/ignition/ig104.htm

[edward ericson]

Smart article. I knew just about none of that. 

[Paul Mossberg]

Ditto that Ed!

Great article!

Thanks Roy!

Paul Mossberg
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica Roadster

If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)

[HappyJack]

Thanks Roy for the link.  Now I know all there is to know about coil polarity.  I did check my coil and it is now installed with the correct polarity. 

I just installed my Pertronics SVDA distributor and will hook up the electronic ignition wires after a much needed coffee break.  That test drive this afternoon in the rain not only tested out my new coil and plug wires, but my windshield wipers and heater vents as well…but I should have installed the side curtains.  Heading out of town was fine, but heading back the other direction gave me a pretty good drenching.  Oh well, both me and the seat will dry out pretty fast as we play in the garage.   — Happy Jack 

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