check coil to see it works

[Kevin71]

How do you trace a voltage drop.  Go along the wire at different spots and check.  Looking for a bad connection is that right.

[Strawdawg]

You put one probe of the meter on one end of the circuit that you want to check and the other probe on the other end of that circuit.

The meter is set on DC volts.

If there is undue resistance in the circuit, the current will take the easy route thru the meter and you will see a small voltage on the meter indicating how much took the short cut.  Normally, say from the back of the alternator to the battery should be close to 0.1v.  On our cars, with the idiotic routing of the factory wiring, it might me a bit more because there are no many connections involved.

This also works on the ground side of the circuits as well.  For instance, one probe on a clean spot of the  firewall to the negative terminal on the battery should give a very small voltage on the meter...if it is more than 0.1-0.2 v, then you have a bad ground somewhere...

Key has to be on and I prefer the engine running to put a little load on the circuits.

[Kevin71]

I did like Chryco said and ran a power line to the positive side of the coil and put a wire from neg to ground and got a spark when I removed it.  The msd power light is on and I am not getting any fire at the plugs.  Can the distributor not be put in right.  I would think even if it was off a 180 degrees the plug would fire just at the wrong time.  Not sure where to go from here.  Any suggestions on how to check that the msd is firing to the coil?

[Kevin71]

Also I just tried to voltage at the coil while the engine was turning over and nothing.  Does this mean the msd unit is bad.  It would have to be putting voltage to the coil when the car is turning over.

[Chryco Psycho]

make sure the reluctor gap is correct  in the dist , the dist should be signalling the MSD to fire the coil as it turns so the coil should be firing no matter which cylinder the rotor is pointed at .
 To me it sounds like the MSD is bad assuming you are getting a signal from the dist

[Kevin71]

It was running before I pulled the engine.  Although the system is 3 years old it probably has had 500 miles maybe put on it.  I wouldn't think anything would be wore out but I will pull the cap and at least take a look. Do you know what the gap should be on the reluctor

[Chryco Psycho]

Factory dist is .008

[Kevin71]

This is a msd billet dist.  I looked at and I don't see how I could get in there to measure it.  But I did notice that under the dist cap all the contact points were slightly corroded.  So I have been cleaning that off.  also the reluctor looks like surface rust around the base so I took some 1000 grit sand paper and clean the edges off to make sure there is good contact there.  I am hopping to get back together this afternoon and try it. 

[Kevin71]

I went online to the msd website and found directions on checking the dist.  I have the billet dist that plugs into the msd.  It has three wires going to the dist.  1 black 1 red and 1 orange.  I am not getting any reading across the black to either the red or orange.  Is the dist bad?

[Chryco Psycho]

good possibility
 Most MSD 6 for example have 2 wires purple & green & you can adapt a stock dist to it & spin the dist to see if it triggers the coil to fire . I have not seen 3 wire units.
MSD should gave some test info on their site or tech help line .

[Kevin71]

I called and talked to there tech support today.  I tested the trigger wire from the msd 6 unit by turning on the ignition and grounding the white trigger wire.  No spark.  They said it supposed to spark when you remove it from the ground like the coil would.  So I am going to bypass the msd unit and wire directly to the dist and see if I get fire.  Keeping my fingers crosssed.  Thanks

[Kevin71]

Replaced the msd box and got it running.  Now I have to get the old gas out and put some fresh and I might be on the road for summer.  Yea haw

[Chryco Psycho]

    

[Kevin71]

Well determined the msd box was bad. Replaced that.  Cranked up but ran horrible.  Drained the gas put fresh in and ran better.  Set the timing.  Seemed to run ok once it warmed up. But still not even so I replaced the rotor and dist cap. Shut it off and cranked today running like **** again.  It doesn't seem to be hitting on all the cylinders.  Could I have put the dist in one or two off and it run like not all the cylinders are firing?  Total timing at 36 degrees.  It seemed like if it the dist was put in wrong it would never be able to set timing correctly.  Is that wrong?

[Bullitt-]

Have you ever checked the voltage to your MSD ignition?  I've seen multiple posts that these need full voltage and like any of these old cars there's plenty of places for poor connections degrading what gets delivered.