Distributor problem

[Doug&Deb]

This is a continuation of my bogging problem. I’ve determined that the vacuum advance is causing the problem. I have another distributor that is actually the correct one for the car. For some reason I’m not getting spark. I’m getting power to the points but not the plugs. Everything is new in the distributor. What am I missing?

[Sniper]

Power goes to the coil, the ground comes from the points to the coil.  The only time you should see power at the points is if they are open.  When the points close you should not see power at the points.

 

If you only have power at the points then they are not closing and providing a path to ground for the coil.

[Doug&Deb]

Sorry, let me clarify. Power at the points when open(test light flashes when cranking). No power coming out of dizzy. The old dizzy works with the same wire connections so it’s something in the dizzy.

[plymouthcranbrook]

Make sure you have the correct cap for your distributor.  Some caps depending on distributor number are taller than others and the center pole from the coil is too far away for the spark to jump the gap to the rotor.  And all caps I have seen fit all distributors as far as I know.

Edited December 26, 2021 by plymouthcranbrook

[Sniper]

Odd, if the light is flashing at the points then power is making it thru the coil.  Which means the coil should be sparking if it is good.  Quick test, from the coil terminal, remove the wire going to the points.  With key on, use a jumper wire to ground then remove the ground from that coil terminal and see if it sparks.  That will confirm the coil is good.  I usually pull the coil wire from the distributor and plug in a spark plug with the shell grounded to test this. 

[Doug&Deb]

I changed the coil and no luck. Runs with the old distributor not the new. The cap is correct I think. The plunger makes contact. I can feel slight pressure when I install the cap. Distributor is a IAT-4011

[keithb7]

Quick easy, no-learning exercise could include pulling the working vacuum advance off and installing it onto the working dizzy assy.

Edited December 26, 2021 by keithb7

[Plymouthy Adams]

people...the vacuum advance IS NOT NEEDED to start and run......nor is it needed to run snoothy to full acceleration/speed....it only is needed if you want better fuel mileage.   Take it off completely/leave it on connect if no hole in diaphgram...or not, your call.....secondly if coil fires one dist and not the other....likely not the coil....check to see if the carbon rod in in the cap.  It is just a one wire circuit....

[Doug&Deb]

The distributor with the bad advance is IAP-4103A-1 . Different advance unit. What am I looking for on the carbon rod in the cap? Should it be touching the top of the rotor. Pardon my ignorance if that’s a dumb question but I’m trying to learn. 

[Plymouthy Adams]

yes....sometimes....these will get damaged and will fall out and lost to the world...odds are if  in place is good.

[Loren]

I would do an examination of your cap, rotor and wires.

If there is a crack or a chip in the cap or rotor, the high voltage will follow it to ground.

Dirt will "carbon track" to ground.

The center electrode can have crud behind it as well.

A bit of modeling clay would tell you if the center electrode actually touches the rotor.

The plug wires should have no more the 10,000 ohms resistance.

The coil wire where it plugs into the cap or the coil could be bad.

WD40 is a good cleaning agent for ignition secondary parts.

Finally make certain somebody hasn't miss wired the coil. On a 6 volt positive ground car the point side of the coil is positive and the ignition switch side is negative.

Wiring it backwards drops the output of the coil 40%.

 

Back in my misspent youth in San Diego, the first good rain always brought cars in on the hook which needed tune ups.

The mechanics would be gleefully singing Queen's "Another one bites the dust!" with the lyrics altered to:  "Another one rides the bus! And another one's down, another one's down! Another one rides the bus!"

WD40 which was created in San Diego should have been in the trunk of every car because a few squirts would have kept them going.

Just sayn'

[desoto1939]

Here is the break down of the correct parts for your dizzy look at 1949 year and then go across .

 

Rich Hartung   desoto1939@aol.com

 

 

[nonstop]

Long time since I have posted.  A couple of questions.  Are all the wires in the distributor in good shape and showing continuity?  When you crank it over with the cap off, are you seeing the points sparking/arcing?  That may be a sign of a bad condenser.  I think it was previously mentioned to check the condenser.  I have had way too many NEW condensers go bad in a matter of months or less.

[Woodie]

You forgot to put the rotor back on?

[wagoneer]

I concur with @keithb7 I recommend bench testing the distributor to ensure it's grounded properly outside of the vehicle. I did a short video on how to do a simple bench test using a drill, jumper cables, battery, and a ground. Getting good grounds is of utmost importance, and ensuring the the points and the rotor are properly grounded as well. In addition there is a soft button in the cap that also can go bad quite easily. 

 

 

Edited December 27, 2021 by wagoneer