PDA

View Full Version : electrical question


BEEF
07-27-2006, 12:02 PM
why will it not work to hook a coil designed to be used with neg ground into an old english car with pos ground. shouldnt the the coil work the same either way?:confused: :confused: :confused: :confused:

NickB
07-27-2006, 01:19 PM
The windings won't be the same. It won't saturate the same. Dam Brits

Tmax
07-27-2006, 01:33 PM
why wouldnt it work? try it and see

In The Zone
07-27-2006, 01:42 PM
it will work just do everything backwards...
u still need proper isolation

Big_Ern
07-27-2006, 01:54 PM
you what he said

isolate the coil from the body & any other grounds since they're positive on this vehicle. Then Hook up a wire from the body to the (+) on the coil, and run a wire from the bat/ign etc (-) to the coil's ground and it should work just fine. You can do that with any neg ground electrical device (radio etc) in a pos ground vehicle. Just be very careful about making sure its isolated.

Tmax
07-27-2006, 01:58 PM
you what he said

isolate the coil from the body & any other grounds since they're positive on this vehicle. Then Hook up a wire from the body to the (+) on the coil, and run a wire from the bat/ign etc (-) to the coil's ground and it should work just fine. You can do that with any neg ground electrical device (radio etc) in a pos ground vehicle. Just be very careful about making sure its isolated.

you cant do that big earn because the motor is also positive end of the coil. everything has to be backwards. the positive of the coil should be hooked to the distributor and the negative side to the frame.

Big_Ern
07-27-2006, 02:34 PM
hmm good point, I forgot about the engine being backwards too...

my idea would work for running a radio tho...

Big_Ern
07-27-2006, 02:40 PM
just did some quick research, looks like it will work if you just reverse the 2 small wires on the coil

Ignition Coil Wiring Reversal.

Look at the wiring on the ignition coil. One side is probably marked SW (SWitch and the other is probably marked CB (Contact Breaker). Your ignition coil may be marked with a + (plus) and a - (minus), instead of SW and CB, as it may have had the coil replaced at some time. Reverse these wire connections. You will test this arrangement at the conclusion of these swaps, to ensure that the coil is wired correctly. If you got it wrong, the car will still run... but not as well.

....

Testing Ignition Coil Wiring Reversal.

You REALLY need to test this. With the ignition off, engine off, pull a spark plug wire loose from a spark plug. Place it loosely back in place.

Now start the engine. Hold a no.2 lead pencil carefully in one hand. With the other hand, pull the loosened spark plug wire slowly away from the plug. You shoud see a good size spark jumping from the wire to the plug. Now... CAREFULLY place the sharpened lead point of the pencil into the path of the spark... you should see a "flare" of particles flying from the pencil lead TOWARDS the spark plug. If you see a "flare" of particles flying from the pencil lead TOWARDS the wire... you have the coil hooked up backwards. Remove the pencil lead from the spark path. Replace the wire. Shut the engine off, and re-reverse the coil low-tension wires and re-test. Get it right!

Why does this matter? If you got this wrong, you will be losing about 50% of your voltage at the spark plugs! Weak spark! Essentially, if the ignition low tension coil wiring is reversed, the coil will... "pull" spark, rather than... "push" the spark. Electrons prefer to leave a high-temperature (high energy) surface (like the center electrode of the spark plug) rather than a low-temperature (low energy) surface (like the arm of the spark plug). More voltage (more spark) is available if the electrons move in the correct direction, in the direction they prefer, from the high-temperature center electrode of the spark plug to the (relatively) low-temperature arm of the spark plug. Test it! Get it right!

Lots more good info at the link here: http://www.lotus-cortina.com/electric/convert.htm Its for doing a complete conversion from pos to neg ground, but most of the theory should still apply

In The Zone
07-27-2006, 03:29 PM
good info....

brain food.....


mmmmm