Yes it is.  I just wanted to make sure I could accurately troubleshoot the problem and not just throwing money at it until it's fixed.  I'm sure it was a bad condenser as the points had been replaced last year and the condenser was 20 years old.  Thanks again for all of your help!

Good to know! It is usually the simplest things.

(....of course points were mentioned in the 7th posting to the thread! Ha ha!)

Now, why did the points melt? perhaps you left it sitting wih the ignition turned on. If the dizzy shaft was in a position where the points were closed, then it would be conducting current., and the metal bits would get hot. Or the condenser wasn't condensing and the points were arcing every time they opened.

Changed the points and condenser and now it runs like a top!  Thanks to everyone for all of the help!!!

The only plastic I can think of on a set of points for a 45D distributor is where the points spring is supported/isolated from the mounting foot of the points.  Is that the plastic you are referring to? 

If so... that should NEVER get hot enough to melt and if it has melted to the extent that the spring is now touching the foot... you MUST replace the points (as I don't think the plastic insulator is available separately).  If the spring shorts to ground it will be like the points never open and therefore, you won't get any spark.

See the picture below (Apologies to our host.  This was the best picture I could find quickly on the net).

About time..................

The plastic that melted is around the point contacts, specifically the bottom contact; the plastic heel block is fine as I've oiled the felt wick well and made sure that it contacts the distributor shaft.  I do have a 45 series distributor (actually an Aldon Yellow 100AYV).

I've dressed the points within the past week, and always check the gap when I adjust them.  However, I did notice that they had a dark blue burned look to the point surfaces when I dressed them last, and I was able to file away most of it.

The distributor cap, though 20 years old, is clean and dry inside and out, only has 1k-2k thousand miles on it, and it appears to be brand new with no issues.  Same with rotor.  I will consider ordering new cap and rotor, but I will definitely order new condenser and points as everything seems to be pointing to the condenser as suspect.

Thanks for all of your help and I'll report back with the results.

Dan gave you a list of things that can overheat points.  I have an additional set of questions and comments related to the earlier information and your last post.

In your March 2nd post you said the points were fairly new.  In your last post you said something plastic around the points was melted.  When did you last dress the points flat and set their gap?  The "melting" on the plastic heel block for points can also come from running the dizzy cam without lube on it.  If the heel block is melted or badly worn then the points gap won't be right and your engine will have running problems and may be nearly impossible to start.

Take the points you have now and dress them flat and reset their gap (or replace the and set their gap).  While you are there, fit the new condenser as Dan suggested.  The 45 series distributors use points that can support a felt wick that rubs against the 4-lobe cam below the rotor.  If you have a 45 distributor, soak that felt wick with engine oil and make sure its inboard end is rubbing on the cam lobes.  Make sure the wick is wet with oil end-to-end and especially where it touches the distributor cam lobes.  The older 23/25 series distributors do not have a lube wick.  You must put a small amount of thin grease on the lobes of the cam to reduce wear and heat.  Any grease is better than no grease.  I have used CV joint grease (which is filled with moly-disulfide) with decent results.

After you have tried a new set of points and the condenser let us know if things are working better.

What do you mean by 'slightly melted'? Which plastic parts?

Melted plasic suggests too much heat from someplace. Given that the points assembly including the plastic are supposed to live in a warm distributor, the heat must be from an excessive source. Since they are supposed to carry 12V  and enough current to fire the coil (it being the 'load'), then the heat probaby came from too much current due to a shorted coil or the leads to the coil being shorted. Both doubtful. The next possibility is that the points themselves overheated due to arcing. The condenser's purpose is to 'cushion' the current across the points so they don't spark when they open. So, suspect the condenser. Also suspect the points assembly in that the plasic is supposed to insulate and if it is melted, it may not be doing its job properly. Usually worn points are apparent from a tooth that appears on one face caused by the spart transferring metal from one contat surface to the other. The only other source of electrical current under the cap is the high tension being carried by the rotor and cap terminals. Rotors have neen known to fail, usually a built-in resistor on some varieties breaking, resulting in poor conductivity across the rotor. The spark may go astray, but not likely to the points. Another problem is a worn or dirty cap. A cracked cap is an obvious problem, but if dust, dirt or even engine oil vapours get into the dizzy, they settle on the inside surface. When the engine is running, the spark leaks across the dirt, carbonizing it as it goes. You end up with a carbon track that bleeds spark charge away and causes poor running. A black carbon line isn't obvious inside a black cap and it can't be cleaned off. All of the above explains why a complete tuneup should consist of new points, condenser, rotor and cap.

Dirt on the outside of the cap and dizzy and spartk plug leads can also cause spark to leak away, especially in damp weather. The popular 'quick' cure is to use WD40, but that leaves a residue that, guess what, collects dirt.

What are the possible causes of the plastic around the points to be slightly melted?

No, I do not think your resistance checks indicate the condenser is bad.  Sorry... technobabble to follow.

A condenser is a capacitor.  When your meter measures resistance it actually passes current through the device you are trying to measure.  When you connect the meter in resistance mode to the condenser you are actually charging it up.   

When your meter reads "1" it basically is saying "infinite resistance"... no current flowing.  When you touch the probe tips together and it reads "0", it means max current is flowing... a short.  When you made your first condenser measurement your meter went "low" then back to "1" indicating that you charged up the condenser.  The next reading you took will not be quite the same because the condener is already charged.  To get the same results from test to test you need to discharge the condenser by touching its wire to ground between each test.  That will discharge the condenser.

That being said, the resistance test only says that the condenser will charge it does not say it is "good".  Condensers are cheap.  Replace it at least to eliminate it as a variable.  If the problem goes away, throw out the old condenser.  If the problem remains, save the condenser you removed to have as a spare.

I tested the resistance on the condenser again, but before doing so, I disconnected the wire going to the distributor and put a piece of paper between the points to hold them apart.  I tested my multimeter by holding the leads apart (it read "1") and then held the leads together (it read "0").  When I touched the positive lead to the wire going to the condenser and the negative lead to the condenser body, the multimeter briefly read a lower reading, but then went back up to "1".  I removed the negative lead, then touched it to the condenser body again, and it did not change fron the "1" reading.  I switched the leads (positive to condenser body, and negative to condenser wire) and the multimeter briefly read a lower reading, and then went back to "1".  I removed the positive lead, then touched it to the condenser body again, and it did not change fron the "1" reading.

Does this confirm that the condenser is shorted and needs to be replaced?  Thanks to everyone for all of your help!

With the condenser in place, were the points open or closed? When closed, the points are grounding the circuit including the condenser's lead. With the points open, the circuit is through the condenser, charging it. Test condenser with points held open with a non-conducting tool - your finger for instance! Plastic knitting needles are useful too.

Iv'e ruled out the fuel pump.  When disconnect the fuel line from the carb and turn the fuel pump on, it pumps plenty of fuel.

I have a Smiths tach with RVI on the bottom of the face.  It has three wires going to it.  One wire to the ignition switch, one to negative side of the coil, and one to the distributor.  If I were to bypass the tach, what do I do with the wires?

I read the voltage at the coil with only the key on, making sure to open the points, and I got 12V.

I also tested the resistance with the condenser in place and each time the reading went from 1 to zero.  I tested several times and swapped the leads back and forth as well.

Any other ideas?  Thanks in advance for your help!

Do you have an electronic fuel pump?  I was having similar problems and kept messing with the carb but I now am pretty sure it's the fuel pump based on what happened to me earlier this week.  I'll know for sure this weekend but thought I'd throw that out there.

Dan

Not true they do work intermittently ask me how i know. Just replace it they are cheap but to be honest the older ones seem to be a lot better quality wise i have had several new ones fail. Is the problem continuous or only there when hot or cold ?

Check your engine grounds and the positive wire under the car to make sure it is not touching the exhaust and shorting out.

I skimmed the responses, so pardon if this was mentioned...

Is it a SMITHS tach? If so, is it an RVI or RVC type? (llook on the tach face near the bottom)

If RVI, the wire from the ignition actually runs through the tach itself before making it to the coil (series circuit).  RVC are voltage type (parallel) and (may be?) less likely to affect the coil, but I wouldn't rule it out.

If RVI, bypass the entire tach. (upon reflection, ditto RVC if all else fails)

 Either could be failing with leaky capacitors &v other failed parts affected coil voltage.(etc.)

If neither, ignore my post and carry on ,

Right! The mark on the pulley/damper can be off if the pulley was changed or the damper rubber is worn out. Or the fixed marks may be damaged.

The factory marks would only be at TDC. There should be 4 lines on the flywheel, the last one at TDC and the others at 5, 10 and 15 degrees BTDC.

Is it possible that the flywheel has a 10 degree mark for both BTDC and ATDC?

A bouncing tach needle can be as simple as a weak connection, or as complicated as all the theories suggested. But backfiring through the carb suggests (in general) that spark is happening while the intake valve is open. That means way too soon.

Start by disconnecting the tach and ignoring it. There may be a fault in its connection or in its innards. If you have a separate tach/dwell meter, use it. If not, get one.

Does the backfiring go away when you disconnect the tach? If so, trace the problem. If not, change out the condenser, check dwell and timing. Verify with the manual whether the vac advance should be disconnected or not during the setting of timing. Note that if it is to be disconnected, you need to cap the port on the carb. Verify that your timing marks are correct - that TDC actually is top-dead-centre. Check timing at idle and at various rpm to ensure that the weights and springs in the dizzy are functioning properly. Note that if you get erratic dwell, your dizzy cam and/or bearings may be worn.

Note also that the vac advance relies on manifold vacuum, and that the port used should be downwind of the throttle. Vac advance is a fuel economy feature that advances the spark at idle to improve combustion of a leaner mixture. As you apply foot-pressure on the throttle, manifold vacuum drops, vac advance releases and the springs and weights take over to manage spark advance in proportion to engine rpm. If your vac advance keeps pulling, you end up with too much advance for the rpm, and the engine coughs.

Similarly, if you have a nice, lean idle mixture and you pop open the throttle, but don't have the right combination of dashpot oil and spring, the dashpot may lift too soon, resulting in an over-lean condition and stumbling or coughing.

When you read the voltage at the coil, was that with the engine running, or stopped and just the key on? As CupCake suggests, a ballasted system will exhibit a lower votlage at the pink coil supply wire. A ballasted system only provides a full 12V (battery voltage) when cranking, through a contact at the solenoid that only closes while the starter motor is energized. Voltage with the coil energized, with the points closed to complete the circuit might show a voltage drop - I'm not sure.  With the points open, you should get full voltage. Try it again, while opening the points by finger. If not full voltage, try, instead of opening the points, pulling the low voltage lead from the coil to the points. If you get full voltage, then suspect the condenser is shorted. If not, suspect the coil is shorted or weak.