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Discussion Starter · #1 ·
Well, I installed the carb/intake heat shield, but I still have the same problem - severe missing at idle and low throttle settings after warmup. Engine runs fine when cold and up until shortly after reaching operating temperature.

Now, I realize that when this happens, it isn't firing on cylinders 3 & 4. I checked and there's no spark to either of those cylinders. However, while pressing the plug wires back into the distributor cap, I notice that if I push the distributor slightly towards the driver's-side fender (not much pressure), cyls 3 and 4 start firing again. It's the same if I press on the cap or the distributor body.

There doesn't seem to be any play in the shaft. It does look like the alternator bracket is fairly close to the distributor shaft flange, so I'm going to see if loosening or moving that out a bit helps.

Anybody got any ideas?

-Bob
 

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Reborn Opeler
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It depends on how you have your distributor timed in relation to your engine, but on mine right now #1 & #2 plug wires are the ones closest to the driver fender. If yours was like this then you are possibly pushing the cap a little closer to the rotor, thus reducing arc gap there. If that is the case it sounds like you have a weak ignition. Like in need of points and capacitor, or new coil. The temperature thing could be the coil. My 66 Mustang back in high school (God rest her soul) had it's coil go bad, and it started misfiring as the coil warmed from the current in it.

Todd
 

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Discussion Starter · #3 ·
Todd,

It happens when I push on the distributor casing as well - not just the cap.

I've also replaced the plug wires and swapped out the coil for a known-good unit, so I know it's not the quality of the spark.

However, when I started to pull the distributor, I realized that the points were barely opening. I just got this car and have not yet done a "real" tune up since the receipts that came with it indicate that one was done less than 2000 miles ago (when the engine was overhauled). So, I never thought of something that simple.

Now I've got to go get a dwell meter. Haven't had one of those in years, but with 5 classics (four of which still have points), it will get a good deal of use.

We'll see how it pans out tomorrow.

-Bob
 

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If you just check for spark directly from the coil tower with the cap off to watch the points, does it always fire on each cam lobe, or does it seem to miss, say, two out of four times. If so, maybe you have a worn distributor bushing, which will cause the points to improperly function. But I would have thought it would happen on opposite lobes, such as 1 and 3, or 2 and 4, (firing order is 1-3-4-2) since they are opposite each other.

Have you tried re-gapping or replacing the points?

I would check the distributor cap and rotor. They have a bad habit of "carbon arcing" inside, and once that starts, it's time for a new cap.

Or, do you have the correct cap. That is, does it fit properly? There should be a small square protrusion that lines up with a corresponding notch in the distributor.

Or, is it possible that the distributor isn't grounding properly? It almost sounds like whe you push the housing, you may be re-establishing a ground. Although that doesn't go around with it only affecting numbers 2 and 4.

That's about all the ideas I have. HTH and good luck.
 

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Point gap should be set to 0.018 inches, and the dwell is 50 degrees.

But if you are interested in a better ignition system, do a search for "Pertronix" on this site. They make an electronic ignitor module that nicely replaces the points (and can easily be swapped back to points should you wish to do so) for about $60, and then you never have to worry about points again. They also can alleviate some of the problems related to a worn distibutor, at least up to a point. Pardon the pun.
 
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