1937 Packard Six, the engine starts and runs fine, until .... misses and sputters

[Leland Davis]

On my '37 Packard Six, the engine starts and runs fine, until I start up a gradual hill in 3rd gear. At that point it misses and sputters, as if it is starved for fuel. Initially I am thinking that the accelerator pump (a leather piston) in the Carter WA-1 carburetor is the problem. A friend said "Just put a 6v fuel pump in as a helper to the original pump", but I want to solve the problem without adding anything to the system, since the car starts, idles and runs so well,  till the accelerating problem. I would like to check the pressure going into the carb, but don't know where to find a 1-5 psi tester, or how to use one.  I also have it in my mind that it may not even be a fuel problem. Any thoughts or hints? 

[carbking]

At cruise RPM, the accelerator pump probably will not be activated, so would seriously doubt this is your problem (although I sell carburetor kits should you disregard my opinion).

 

You can easily test the fuel pump's function by accelerating HARD through first and second gears. If you get through second gear without running the carburetor out of fuel, the fuel pump is fine.

 

My initial guess would be that you have ignition issues, probably timing, or a distributor that is not advancing properly.

 

Jon.

[Oldtech]

If you have a vacuum gage most will have a scale for reverse vacuum ( pressure actually) for testing old fuel pumps.

 

The accelerator pump only works when the accelerator is actually being depressed. In a constant load situation, it is not involved.

Edited May 21, 2021 by Oldtech (see edit history)

[M1842]

Test the distributor vacuum to see if it holds vacuum, if not it will not advance the ignition as you try to accelerate.

[Leland Davis]

Good idea... but how does one test the vacuum? I would assume there is some sort of gauge that is put in line while the engine is revved?

[rocketraider]

1 hour ago, M1842 said:

Test the distributor vacuum to see if it holds vacuum, if not it will not advance the ignition as you try to accelerate.

Vacuum drops under more throttle opening? Maybe distributor mechanical advance is sticking.

 

Yes, Leland. Connect a vacuum gage to an intake manifold vacuum tap. Vacuum readings can tell a lot about an engine's health. At normal idle, vacuum should be fairly high (17-19" Hg) and steady.

 

A simple and quick vacuum advance test is to remove distributor cap and suck on the vacuum tube to the advance diaphragm. If it moves, it's probably good.