Which Ignition Coil For My 73 tii?

[PaulTWinterton]

I've read many of the posts about coils and colors.

I have a stock 73 tii with a Blue coil attached to the ceramic resistor on the fender. Has been that way since I bought the car 22 years ago.

Should I replace that coil and/or configuration? I don't believe the car is running or starting quite as well as it could and I have nothing else to adjust or replace.

I want to stay as "stock" as I can.

Coil advice please.

Thanks,

Paul Winterton

Vancouver Canada

73 Inka Tii, #2762958

[bnam]

I believe you need to remove the external resistor if you're using a Blue coil as it is internally ballasted -- so you've right now got it with 2 resistors -- thus decreasing the voltage quite a bit.

Try that first.

The non-ballasted coils would be the black or red ones which need an external 1.8ohm resister I believe.

Byas

[02fanatic]

If I remember correctly, the stock ceramic external resistor on the tii is 1.8 Ohms (non-tii is something like 1.0 Ohms)....I'd say goodbye to that blue coil "like yesterday"! :-)

Buy a red coil.....actually, nowadays it's silver. I'd have to dig up the part number...but, personally on a tii, I'd never pitch the external resistor in favor of the blue coil. The proper coil is what you need. Actually, the original black tii coil is "the best" way to go, but they are long time NLA I believe.

Finally, here's some good info from my good buddy (who many of us still miss terribly)...good stuff!

Date: Thu Jan 24, 2008 11:39 pm

From: ingraham in Oakland, CA

Subject: How to measure a small resistance ...

It's a challenge to accurately measure a small (< one ohm) resistance, because most ohmmeters are not designed to do that well, and the test leads plus the contacts between the test leads and the circuit being measured can have a resistance of a few tenths of ohms, and it might vary with how you hold the probes. Here's how to get the best measurement.

Setup:

1. Turn on the meter.

2. If the meter is not auto-ranging, set it to the lowest resistance scale.

3. Touch the leads together.

4. If it's an analog meter, set it to zero ohms.

5. If it's a digital meter, observe the reading.

6. Touch the leads together at different angles to see if the reading changes.

7. If it's an analog meter, reset to zero.

8. If it's a digital meter, note the final, lowest reading.

Take the measurement:

1. Touch the test leads to the circuit to be measured.

2. Hold the leads at different angles or different contact points to find the lowest reading.

3. If it's an analog meter, you're done.

4. If it's a digital meter, subtract the lead resistance of step 8.

_________________

Curt Ingraham

1972 2002tii, 1976 2002

Improved 2002 Radiators

--------------------------------------------------------------------------------

Date: Fri Jan 25, 2008 12:01 am

From: ingraham in Oakland, CA

Subject: Where to measure ballast resistor wire resistance ...

... on a '74 tii.

See the post regarding how to measure low resistances.

Turn the ignition switch off.

Remove Fuse 12.

Unplug the resistor wire from terminal 15 (+) on the coil.

Put one ohmmeter test lead on the free end of the resistor wire.

Put the other test lead on one of the Fuse 12 terminals, then the other.

Measure on the side that gives a reading of 1-2 ohms.

The resistance should be 1.8 ohm for a tii and 0.9 ohm for a non-tii.

(You may have a black/red wire on terminal 15 of the coil. When measuring, you can leave the black/red wire on the coil, or you can leave it connected to the resistance wire, or it can be disconnected from both.)

_________________

Curt Ingraham

1972 2002tii, 1976 2002

Improved 2002 Radiators

HTH,

John

[PaulTWinterton]

I've learned since posting this thread that the consensus is "Black" on the older tii. BMW says NLA, but Blunt has, so I'm replacing one last piece of the puzzle that is my tii. 99.5% stock.

I'm curious and excited to see if it changes anything in performance of the car. Starting? Idling? Acceleration?.........

Thanks for the input,

Paul Winterton

Vancouver, Canada

73 Inka Tii #2762958

[bnam]

Until you get the coil from blunt, try your current set up without the ballast. So, when you put the new coil on, you'll have a better comparison vs. the Blue coil.

B

[harry6422]

I just bought a Bosch new red coil #00013 from AutohausAZ for 45.88!! , it is the perfect match for your 1.8 ballast resistor. I am using this set up on my 75 2002,you need to remove the resistor wire on the later cars, hotter spark than blue or black coils , for better starting spark you can run a wire for the starter, look at the later cars wiring diagram to as which terminal to attach it, this buy passes the ballast at starting when the volts are low . AutohausAZ ships free over $50.00 and no tax so order a oil filter and get free shipping:) They have great pricing, link below:

www.autohausaz.com/bmw-auto-parts/bmw-2002-parts.html

Harry

[Chi-Tii]

I have gone back and forth with Red and Blue coils on my '72 Tii.

I had it set up to easily swap back and forth when I was playing with a MSD+Pertronix setup.

Make sure to do the Ohm test. You can do some serious damage if you get the wrong combo of resister and coil. When I got it wrong, I melted a rotor in my dizzy which turned the cap into a plastic "grenade" while I had my head in the hood.

I have a Blue Coil with the Pertronix kit currently as it was the smoothest ride for me in the end, but will take a look in the morning as my Red Coil setup is still in there, if you still need a hint that is.

[JohnS]

Paul,

Just make sure that you use the proper resistor with that new Black coil. The coil should have a label on it which states the resistor to use. Your tii is probably using a 1.8 ohm resistor. You can check on the resistor to see if it is marked 1,8 on it's metal base. Some black coils require a 0.9 ohm resistor. If that's the case, you might have to swap your resistor for a 0.9 ohm one.

If you're running a Petronix, you want to hook up the positive wire of the Pertronix unit before the ballast resistor so that the Petronix gets full 12+ voltage.

Good luck,

John

[PaulTWinterton]

John,

I wasn't expecting a challenge, so yes, I'll check carefully that the Ohms match. I hope so, as I don't have another resistor sitting around.

Thanks for the heads up.

Paul