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

hi All i have rebuild my WGD carb with a new kit, bcz it was running about 5 galons on one mile , i set it to all specs.( float etc.) but some things still dont run that good.
for instance the engine only runs and idles with the choke set very loose, it has to be half open to get the engine started, also the engine doesnt react on the 2 screws for idle mixture, i can turn the screws clockwise till they are shut, and still the engine idles at the same speed.

could the choke problem be due a bad vacuum? (it wont open when i set the choke valve to the manual specifications)

the engine runs tho, smooth idle, and also runs good at high speed, still drinking more then i do.

but i dont think its normal for the choke valve to be open all the time, anyone any ideas where to look at?

The two screws you refer to are for the idle mixture jets. They increase or decrease the amount of fuel mixed with air for the engine at idle speed. Turning the screws in reduces the fuel, and turning them out increases the fuel. If the engine runs with the screws turned all the way in, the carburetor is providing enough fuel for the engine to run without using the idle mixture circuit. Either the float setting is too high or the needle and seat inlet valve is leaking. There is an idle speed adjustment screw too.

Usually, the starting place to set the engine idle is to have the idle mixture screws turned out one or one and one-half turns from where they bottom when screwed in all the way, and with the idle speed screw making contact with its stop on the linkage.

After the engine is running and warm the idle speed is set. With the idle speed adjustment at the specified speed, the mixture screws are turned in until the engine starts to slow then screwed out until it is smooth (usually one-half turn). You will need to go back and forth with the idle mixture screws and the speed adjustment to achieve the correct idle speed, ending up with the idle mixture screws. Both idle mixture screws should adjusted be about the same.

The choke plate should be fully released when the engine is warm. It should be just closed on a cold engine.

Of course, all of this is dependent upon the distributor points and ignition timing being adjusted correctly.

I hope this helps, good luck.

(o{I}o)

JW's advice is spot-on, as usual. However, when you say you rebuilt the carburetor, I'm wondering if you removed or loosened the screws that hold the throttle plates to the throttle shaft? They must fit very precisely, and they are not symetrical so they could possibly be installed incorrectly. The edges are precision ground at an angle to form a tight fit in the bore when the throttle shaft closes. Should they not close tightly, you will be unable to obtain a proper idle mixture setting.

Also, make sure you have no vacuum leaks elsewhere; intake manifold gasket, vacuum booster portion of the fuel pump, wiper or washer motor, etc.

Though it doesn't take much practice to set the idle mixtures by ear as JW describes, many folks like to use a vacuum gauge. Attach it to the intake manifold, BUT NOT so that the booster pump can interfere with the reading. Then run each idle screw individually in until the engine falters, and then screw it out until maximum engine vacuum is obtained (18+ inches and rock-steady for an engine in good condition).

John, Thanks for answering Jerome's question . As usual your advice is very good as is O_D's. I suspect that the float is too probably set too high or the needle and seat is leaking also. If the car can be started with the choke plate open it is likely getting too much gas and the poor mileage might indicate a vacuum leak somewhere. I adjust the carb on my Packard using a vacuum gauge which in this case would also show a vacuum leak if one is present if the reading is low. I tap the gauge into the small plug on the intake manifold which is probably present on this Packard also. Where you are in Holland adjusting for altitude above sea level will not be a problem so shoot for 18 In/hg.!
Attached is a just one link explaining how to read a vacuum gauge. A very simple but invaluable tool!
http://www.classictruckshop.com/clubs/earlyburbs/projects/vac/uum.htm
tot zien!

Thanx for al the information, i havnt removed the throttle plates when i rebuild the carb, just gave it all a good cleaning, and the float level was set as shown in the manual, even the needle and seat are renewed, so i would go for the vacuum then. When i set the choke valve spring to the specifications, by turning it clockwise to the arrow, the choke valve is very tight, i have to push it open with my finger in order to fire up the engine, but from the amount of pressure u have to use to open the valve, i would say u need alot of vacuum to get that done. when u release the valve it shuts and the engine stops. thats why i have now set the valve very loose till the valve is half open from the start. seem to work for now, but still uses too much fuel.

Jerome, The choke plate should be adjusted just so it is closed as mentioned by JW. When you open the throttle linkage the choke plate should be able to be pushed open with just a little effort so maybe you have the choke adjustment spring wound too tight? When the engine is warm the choke plate should be vertical. Check for a vacuum leak is a good idea also. Let is know how you are doing.
tot zien!

Ever get anywhere on this? Just had mine completely rebuild and have some leaking internally also, have to have the choke 1/3rd open to get it to start. I'm thinking my pressure might be too high from the new pump, or that it may be needle and seat as they suggested to you. Taking it apart today to check things and see what i find out, if anything seems to help i'll pass it on.

Hi Cordcomp, well i`m still fighting with it, took it appart checked the float level once more and checked the new needle and seat for anything sticking in it, assembled it again, .. but still with the same results, choke have to be very loose and half way open to get the engine started.
i also have a electrical fuel pump, maybe thats a problem too, wonder why they have done that, thinking of rebuilding the mechanical fuel pump. also i will replace all vacuum hoses i have seen some where a litle loose, old and dried up. lets hope that helps a litte.

after all that work it better works! if not.. i will have to find me some new carb.

good luck with yours too!


pfff i was looking for someone to renew the chrome on my bumpers... they dare to ask 2000 euro!!!

i also have a electrical fuel pump, maybe thats a problem too, wonder why they have done that, thinking of rebuilding the mechanical fuel pump.


Jerome,
Are you running on electric fuel pump or using only for start up after prolonged sitting?

Reason for asking if using electric for driving do you have pressure regulator in line? If not probably too much fuel pressure as only needs app. 7lbs pressure for carbs.

I would think for a straight eight carb, in would be more like 3-4psi.