Running rough under a load

Hello
Just replaced the exhuast manifold on my 64 E-van it was runing great prior to this. When i bought the manifold it came with a cast iron insert, after getting it back together I took it for a test drive. It would not accelerate smoothly jerking back and forth until I pulled the choke out a little. I tried adjusting the air mixture still no luck? I removed the manifold and took out the insert, and still it still will not run right? Starts right up idles revs up fine just when driving in gear under a load it acts up with the choke out a little it will accelerate?
Any help would be greatly appreciated.
Thanks Rally72

I was gonna say a vac leak, the Governor most likely
has you on the right track...

Fuel Filter?

bump the distributor? timing? vac advance on dist or line bad or off??

Wierd thing is it ran fine before the exhaust manifold was replaced? I Had a vacuum leaked fixed and timing set prior to manifold being replaced. I have a inline fuel filter that looks clean, however I did fill the gas tank up for the first time prior to the repair. Does it have another filter in the tank that could be clogged up?
Rally72

No filter in tank, but there is a screen on the end of the pick up tube on the sending unit. If your screen is gone you may have sucked up some junk and plugged the tube slightly, or your screen could be plugging up also, but not enough to not let it start and idle or even drive at slow speed. Has this tank been cleaned before or is this the first time in years that this tanks been used?

You can check the fuel pump by disconnecting the line to the carb after the pump. Connect a hose and run it into a small container and then turn the engine over on the starter.
If you have access to a vacuum gauge, you can check the pressure at the manifold to see how the engine is running.

I started my van for the first time after just filling the fuel tank. When the van was running rough, i took the fuel tank out and discovered that the fuel pick up pipe and the fuel sender were completely rotten... Worth a look....

If your not sure of the fuel source being any good from the tank, try hooking the line from the fuel pump to a gas can or boat tank full of gas and see if the motor runs better at higher speeds. This will eliminate the fuel tank if there is no difference. I ran mine around the yard on a lawnmower tank that I hooked the fuel pump to. Just some suggestions so we can eliminate the fuel tank. But if this tank is original and you have never had it out, I would remove it and check to make sure it's not dirty inside and definitely check the sending unit for rot...as mine was rotten also.

I no you probably don't want to here this but I will throw it out there anyway.... If your motor was running really well before you changed that manifold and you had not used the fuel tank before this, you may have opened a can of worms. Blockage in the fuel lines from crap in the tank if it got passed the sending unit screen. crap in the fuel pump because of said cause, and hopefully it all stops at a fuel filter before any of this made its way into your carb. Try a seperate fuel supply and see if that helps, at let us no any info on your tank.

Nothing
I purchased a meter to check the vacuum hopefully by this weekend I can figure something out.

Sounds like the carb was sinked to an engine with a bad exhaust leak. It may need to be retuned with the good gasket. Exhaust leaks have a funny reaction to running sometimes. Hopefully it didnt burn a valve slightly.

This is a longshot especially since you stated that "with the choke out a little it will accelerate"

When I bought my truck it ran ok, had a exhaust leak at the manifold, even though you could see that it was a new gasket it was leaking...I took it apart, put on a new gasket and then when I started it, it ran very bad, would not accelerate and just died, I immediately suspected blocked exhaust because of mice infiltration, pulled the muffler and it was packed full of dog food, completely choking the exhaust off not allowing the engine to run, cleaned out the muffler and voila, ran good. Im just saying...

I seriously doubt you have dog food in your muffler, but I have seen double wall pipes collapse inside, restricting exhaust causing poor performance.

Exhaust pipe clear
But funny you mention dog food I have three dogs, with my luck it could have been dog poop!