Packard Forum Index » Post-War (1946-54)

Remove distributor cap. Just disconnect the tube going to vac advance, stick your mouth on it and suck on it. WATCH WITH TWO EYES to see if the points plate moves or not.

There's also weights in there that causes a change in timing. So just looking at it with a timing light does not check the Vacuum Advance. Like PackardV8 said hook up a hose and use some sort of a vacuum device. But still I would run though the basic engine tune-up.
Wes

If you're not comfortable with pulling the carb, take it to whomever rebuilt it. It's probably just got a little or alot dirt in it, a float issue, etc.
You didn't say if the fuel system was cleaned, so I suspect some type of fouling coming from it that prevents adequate fuel when required for the rpm. Fuel pump could be failing, but probably OK and you'll know when it goes completely.
Pre-electronic electrical systems usually aren't as selective to not run in a speed range. You have good spark/no starting issues, and power returns after fuel has not been called for.
You can monitor the exhaust gas ratio to check for starving, but need equipment. So probably best to take to a mechanic/auto shop.

The problem could be something as simple as a plugged fuel filter. JWL

If the electric fuel pump is the vane type, and you have it shut off during running, very little gas will be allowed to pump through it.

With no diagnostics done or reported, we're just throwing a handful of corn at the barn door. But if the problem is within the distributor it's far more likely to be the centrifugal advance and not the vacuum advance. And failures of the mechanical advance are very uncommon. Put your timing light on and just rev the engine from an idle up to some higher speed - if the timing changes I think you can look elsewhere for the problem. My inclination is that it's fuel related so the next diagnostic I'd do is fuel pump delivery (volume and pressure) and of course check any rubber sections of the fuel line, especially those on the suction side.

But before that, check the fuel filters as others have already suggested and don't forget that many mechanical pumps have a fine mesh brass screen above the fuel bowl, and likewise many carburetors have their needle and seat protected by a similar mesh screen at the fuel inlet.

Get a good service manual with a diagnostic section applicable to all cars, a Packard is not different. I could list 50 or 75 things to cause this problem and you may go broke trying to figure it out, I use books and brains, suggest you do the same.

Do not forget many electric fuel pumps also have a filter -I experienced that problem

Another thing to check is mentioned here in this blog in #42.