Carter 2bbl carb question

[bhclark]

I've got a 401 with a 2 bbl carter carb. The carb has what I call a flat spot. If you give it a little gas, it's okay, if you give it just a little more, it starts to stall(and frequently does under load), if you give it enough gas to hop over the flat spot, the car moves just fine.....albeit with a bit of a jerk.

The carb operates the same whether the car is being driven or operated manualy.

any assistance would be greatly appreciated!

Thanks!

[Guest brh]

I don't have my Motors Manual handy but a flat spot can be caused by other things too, such as timing. I will see if I can locate it to give ya a list of things to run down. If it is the carb my best shot would be the accelerator pump, which if you change it you might as well rebuild it. Sorry for the lack of info.

[bhclark]

Well, I've done a little more research. The carb appears to be freshly rebuilt, as it is spotless. It is a model 2980S. Here is where it gets interesting. The Invicta is a 1959. According to my research the Engine is a 1962 401 (based on the I in the engine number) The carb, according to "the carburetur shop" belongs to a 1960 364 and is a WGD vs a AFB(What does that mean?). (which explains the 364 etched in the air cleaner).

So, does the carb being designed for a 364 instead of the 401 it's attached to have anything to do with my problem?

My 65 wildcat wants to run away at idle.....where the 59 Invicta has to be convinced to go.....is this the 2bbl vs the 4bbl or does this have more to do with the different transmissions. (I have not crawled underneath to identify the transmissions yet)

[Guest brh]

From what I understand out of my parts books The model 4600 (Invicta) could have either a Rochester or a Carter 4 bbl. It does not show any 2 bbl carbs for either the 62 or 59. The engine may simply be starving for more gas. As to the number you are refering to I could not find anything. Hope this helps.

[variablepitch]

I think that the Invicta 401 had either the Carter AFB (aluminum four barrel) or the Rochester 4GC. I suggest that when the car is cold, like in the morning for example, take the top off the air cleaner, don't start the car, just move the throttle lever a little and see if the automatic choke butterfly closes. If it doesn't, maybe the setting is too lean. Is the heat source pipe to the exhaust manifold there? Also, you might check the heat riser valve in the inside of the exhaust manifold next to the engine block. It needs to be free to redirect some heat to the base of the carburetor when the car is cold. My car hesitates some also until it warms up. I think it's time for me to do the carburetor. With my 35 year old auto mechanics degree and the factory manual, I seem to get the job done. The fast idle cam on your '65 must work fine if it runs fast when it's cold. If your other Buick doesn't, I'd start checking the heat riser, and choke settings and freedom of movement of the choke linkage.... Hope this helps you.

LeeB

[carbking]

The 364 and 401 have a different fuel profile. Using the carb designed for the 364 on the 401 would cause some fuel issues at high vacuum. As the vacuum dips below the tip-in for the vacuum piston to operate, the metering rods would be raised and use the midrange calibration, which sounds like is working.

A temporary fix might be to raise the fuel level in the bowl a 1/16 of an inch. This can be done by changing the thickness of the gasket under the fuel valve. I would not recommend raising the fuel level more than 1/16 of an inch.

A better solution would be either changing to the four barrel setup used on the early 401's or changing out the 364 two-barrel with a 401 two-barrel.

This link will give you the various applications:

Buick carburetors 1940~1966

Jon.

[bhclark]

Great information! The Carburetor shop is where I did my research. I was afraid that the wrong carb might be causing the problem. I will test the theories and do some shopping for a replacement/correct carb. Any idea on where to get a carb other than Ebay? In this era, do I have to worry about the linkage lining up or will any carb designed for a 401 work just fine?

Thanks!