weak spark
 

Hi all,

I have a transistorized coil (blue) and I noticed the spark was yellow and did not make a snapping sound. I'm also getting about 12 MPG with my 72 250 M130 W114.

I'm wondering if the coil is bad or the polarity is reveresed. There is a wire that's comming from the front driver headlight area to the negative coil. Is that correct?

Thanks all.

Ok, Just put the multimeter on it, with the ignition on, engine not running, I'm getting 1.87V on the - side and 0 on the positive. That doesn't sound right so I flipped it.

Was that correct?

Be careful. Some cars of this vintage run with the lead to the coil to +.

Also, I don't think a blue coil is right for the transistor ignition that you have. The blue coil is great if you go to a Pertronix setup, which seems to solve a lot of problems.

Coil
 

The spec is 2.8 to 3.2 volts to the coil positive.

Sounds like you have a corroded connection to the 'Run' ballast resistor, a bad ballast resistor, or a bad Transisortized switching box.

BTW, I have been connected to the the - coil side, with the positive side grounded to the chassis for 3 years. No problems.
I read an article how Spark plugs require negative spark energy.

Hey Munich,

Just to make sure I'm measuring right, I'm using the ground post from the battery to the positive post on the coil.

Chuck, THanks for the advice, but I took her for a spin and OMG what power, she actualy peeled out of first and second. I AM SCHOKED!!!!!

So, what did you do?
 

You gave us the result, without the 'method' that delivered the performance change.

With the normal set up, the voltage to the + coil is 2.8 to 3.2 volts, when the - coil is grounded.

However, to tell you the truth, I never went back and measured the voltage to the - coil, after I made the reversal. Hmmmm...

That was it. I just flipped the wires for terminal 1 & 15 after I noticed the + had 0 volts and - had 1.8. Again, this is not measuring accross the coil, only from the ground post.

Is that where I should be measuring?

Munich do you have a troubleshooting procedure?

Thanks