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

I am having some issues with my 51 200 with 288ci engine. This engine was rebuilt in 89 and driven off and on about 1000 miles since then. Some accessories were rebuilt too such as the carb, distribruator, starter, and generator. The compressions are very good 6- 120 1-125 1-115 hot. I have had an issue with hesitation on acceleration. I had though it might be then accelerator pump in the carb. So I cleaned and rebuilt the carb, but nothing changed. However I found something like epoxy on the intake manifold, under the carb maybe to repair a crack. I pressurized the manifold with the discharge from a Vaccuum cleaner, and soaped the manifold to see if I could find a leak, but nothing. I have already replaced the plugs, points, cap, rotor, check timing. Plug wires look good. The paper gas filter before the fuel pump has been changed. Is there a screen in the bottom of the fuel filter? Anyway my question is how do I mount the Vaccuum gage to the engine. Do I use the carb to distribruator line, or somewhere else? I may have an issue that the gage could show me.

Measuring manifold vacuum via the port on the caruburetor for the distributor vacuum advance will not give a true reading. If you don't see a removeable plug somewhere on the manifold, then remove the vacuum line at the intake manifold going to the vacuum booster section of the fuel pump, insert a suitable fitting, and take your readings from there. An engine in overall good condition should show 18-20 inches of vacuum and rock-steady, no fluctuations of more than 1 inch or so.

Typically there is a screen mesh filter in the fuel pump and at the carburetor inlet.

Regarding your hesitation, if you can drive along at 50+ mph or so w/o problems, the hesitation at lower speeds isn't likely to be lack of fuel but it's a classic symptom of a leaking distributor vacuum advance diaphragm. You might also check your ignition timing if you haven't done so already. Easy enough to check the integrity of the diaphragm in the vacuum advance, just remove the line at the carburetor and with your mouth try to draw and hold a vacuum. Failure to be able to hold a vacuum indicates failure.

Thank you I will check distribruator vacuum as suggested. Do I just remove the center bolt under the fuel pump to flush the screen? Will look for vacuum port on intake manifold.

Would removing the hose on the wiper motor of a 48-50 Packard and hooking the vacuum gauge to that line be a good place to check the vacuum of the engine?
Thanks,
Mike

NO! A reading taken at the wiper motor will be influenced by the vacuum booster section of the fuel pump and will not indicate true manifold vacuum.

OK, thanks!
Mike

Well the Vaccuum test plug WAS on top of the intake manifold. I tested vaccuum it was steady at 18psi. I removed the drain plug from the fuel filter, and some large rust particals fell out. Everything is running better now. The hesitation on acceleration is gone, and I can blip the engine. I still get a jutter when accelerating so I will pull the drain plug from the fuel tank to see what's in there. I am planning on a valve adjustment soon too. This car sat for 20 years mostly after it was rebuilt, and it looks like a good clean, and adjustment may set it right. I noticed that there is a short between the starter switch on the carb, and the wire going to the heater fan. Some times the fan just come on be itself. This started after I rebuilt the carb. I must have flexed the wires

A steady reading of 18 inches of vacuum is quite acceptable. While the gauge is still installed it's the best way to set your carburetor idle mixtures and you might gain a bit more by doing so. With the gauge installed, adjust to maximum vacuum and then turn back in (lean) until it just begins to drop, then back to the maximum again with the screws out no further than needed.

Rust flakes in the fuel pump sediment bowl isn't at all uncommon. If it's made of metal and is itself beginning to rust you might consider some sort of gasoline-resistant coating on the inner surface after cleaning it. I believe they were originally plated to prevent rusting.

... so I will pull the drain plug from the fuel tank to see what's in there.

A word of caution. You said the car had been sitting 20 years. If the fuel tank was not removed and cleaned at some relatively recent point with the drain plug removed or changed at that time, if the original plug has been untouched for 20 years be very careful when trying to remove it. The original steel plug may well have rusted to the threaded tank portion which is only pressed or crimped into the sheetmetal.

If trying to remove the plug without holding the tank portion with large vise grips or whatever gripping tool you can maintain a good holding bite on the tapered sides then the tank portion will likely break loose and turn with the plug. From that point on you will haves a very very difficult to repair leak.

If you do remove the plug, it would be a good idea to replace the steel plug with a brass plug.

Great advice from HH56 about the plug and possible damage to the tank when trying to remove it; I've replaced both of my drain plugs with brass.