I was driving the 66 mustang to Pigeon Forge today for the Grand Fall Rod Run and had ascended up over the mountains without a problem, but on the way back down the engine started sputtering as if it were running out of gas. It didn't die, just sputtered without any power. When I tried to accelerate, I would get no power. When I tried to idle it, it died. Initially I thought the plugs had fouled. The first thing I checked was the fuel. The accelerator pumps squirted plenty of fuel when the accelerator linkage was advance. There did not appear to be any problem with the gas supply. I then checked the ignition system starting at the plugs. I pulled #1 and #8 plugs, both were dry with a trace tan residue. (This engine only has 100 miles on it since my rebuild) I pulled off the distributor cap, and the inside of the cap and the rotor were fine. I have a "K" dual-points distributor. With the ignition on and wiggling the rotor back and forth, I was seeing sparking at only one set of points. I cleaned the contacts on the bad side and got sparking at both sides. Still sputtering... I checked the voltage at the battery terminal on the coil, it showed 5.5V. Is this correct? How far down should the voltage regulator step down the 12 volts voltage to the coil?? I loosened the distributor hold down bolt and tried advancing and retarding the timing but either direction only made it run worse, so I put it back at the original timing.

I'm planning to replace both sets of points, though I'm not sure why the points would be bad at only 100 miles. Should I replace the Voltage Regulator as well? The distributor is brand new, the coil is brand new, the wires are brand new, the plugs are brand new, the timing gears/chain are brand new.

Can anyone help me out?? Where should I go from here?

Tom
Bryson City

 

Depending on the coil, it should be a 6 volt coil. SO that 5.5 might be to low for that coil.

 

Should be 9V right? 5.5 is too low. Popping and sputtering is common with low voltage from my experience.

 

i think it's a 6 volt coil. Thats why they have that resistor wire, to lower the voltage to 6 volts.

 

what was the altitude difference??
it may have been getting too much gas
is it running ok on home turf?
just a thought!?!?!?

 

No, not running any better on home turf. Does ANYONE knopw what the voltage should be at the coil?

Tom
Bryson City, NC

 

Points create ignition spark when they OPEN, collapsing the coil and sending a HUGE voltage to the dist cap. My experience is, they use dual points to allow a longer ON time (points closed), to saturate the coil. It isn't unusual that you only see sparks on ONE set of points, as that is the last one to open.

Did you notice black smoke coming out of the exhaust (possibly from a very rich mixture)? Or, does the engine run sluggish throughout the rpm range? Your initial question made me think of a plugged gas filter (starving only at high demand), which might let the engine idle smoothly, carb pump squirts will look healthy, and everything looks good in the garage, but not on the road.

If you could, be more specific in your description of what's really happening, and when. Your ignition coil sounds just fine.

 

Just a quick update, I ordered two new sets of points, and a new condenser. Once they were replaced and I adjusted both sets, the engine fired right up. It's not running as well as it was before, but that's because I let some helpful roadside hands tweak my timing, idle mixture, idle speed adn who knows what else they adjusted. I've since got the timing readjusted, mixture set better, and idle speed corrected, now running much better and completely driveable.

(Also ordered a new 07' Jeep Rubicon Unlimited 4-door!! Woo-hoo) but that's neither here nor there.

Tom
Bryson City, NC

 

Just for future reference, you should be getting about 9.8 volts DC to the + side of the coil. Anything below 7.5 and you start having spark problems, especially if you are running a pertronix ignition module.

 

And if it's less than 9.8V would that be the voltage regulator?

If less than 9.8V, would that burn up points? Condensor?

Tom
Bryson City, NC