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

I have a 1947 Clipper 8. When the weather is over 90 degrees, my car acts like it is not getting enough gas after I drive for awhile, especially in traffic. If I go less than 15 miles per hour, it may not stall, but if I depress the gas pedal more it will stall. Then, it is hard to start.
I would like to rule out the heat riser. The spring is missing, but the counterweight moves freely and stays down. Does this mean it is holding the valve open and I do not have a problem?
I have a clear fuel filter right at the carburetor, and I can see fuel in it. I am using an electric fuel pump which is near the fuel tank, and if I disconnect the line from the carburetor and turn on the ignition I get good fuel flow.
I have read several threads here about vapor lock, but before I do anything significant, I would like to know if my symptom is really vapor lock.

Dear Harry:

Get a KD spark tester from NAPA and check your ignition. You should have at least 20Kv of good regular spark. It sounds like something is heating up and causing a bad connection.

Harry: Good advice from Tim. Often heat will cause older ignition parts to fail. If your ignition system checks out try a 5% mixture of diesel fuel in your gasoline. It cured a bad vapor locking problem in my 47 Custom. I would think that your electric fuel pump would over ride any vapor locking. I think Austin climate is as bad as Florida's in the summer.

(o{}o)

I pumped all the gas out of the gas tank using the electric fuel pump. The gas was brownish. I then blew out the fuel line with an air compressor and put a new fuel filter near the carburetor. I put new fuel in and it started right up. I set the KD spark tester at 20Kv and got good spark. I let it idle and measured the temperature on the exhaust manifold and was surprised that it was near 500 degrees near the front. I advanced the timing and the temperature came down to 400 degrees at the hottest spot on the exhaust manifold, but most readings were nearer 300 degrees. The base of the carburetor is 160 degrees. I am now ready for a test tomoorrow in the afternoon heat.

I hope my problem was just old gas and retarded timing.

Any results to report on your field test, Harry ?

I have been having what sounds like the same issue with my '47 Clipper 6. When the car starts the "starved gas" symptom whle accelerating, and stops, I usually see gas bubbling in thenglass bowl filter next to the carb.

It's very frustrating.

Thanks to everyone for being there.

Best regards,

Dave Blandford
Cell 513-205-3188

A common problem on the inline Packards. On my 51, I fabricated a new longer line and routed the gas line over towards the right fender and away from the manifolds. I also took a rubber fuel line that was slightly larger than the steel one, split it longwise and placed it on the steel line. The cut is facing up. This seems to have helped the heating of the line and knock on wood has solved the fuel vapor lock. Course I also switched to Exxon Premium gas, which in MT has no alcohol. That helped quite a bit in the performance section as well.

Do you have all the factory heat shields in place? The should be one between the manifold and the fuel pump, and on some models there is one by the carb.

Also make sure your heat riser is working correctly, and you have the proper insulator block between the carb base and the intake manifold.

Vapor locking is most likely to occur in the un-pressurized part of the fuel system (line from tank to pump and carburetor bowl). That is why electric fuel pumps are generally mounted close to the gas tank, so the fuel line to the mechanical pump can be pressurized. Not much you can do about fuel in the carburetor bowl boiling. High altitude will also enhance the problem. I run a 5% mixture of diesel fuel in the gas tank when the weather gets warm and in Austin that is pretty much all year 'round. This seems to work well for me.

(o{}o)

See if you can find the timing marks on the damper. It may take a while, but setting the timing with a light makes a big difference.

If you find them use some white out or paint.

Another check is to put a vacuum gauge on it and advance to the highest vacuum then back off 2 inhg on the gauge.