The Stovebolt Site Forums The Shop Area Engine Shop 261 running rough

Hi there, first time posting here on these forums. I have a 62 with a 261 inline six and have been having some troubles with it. It really doesn't like to start, regardless of it being warm or cold. I often have to squirt a little starting fluid down the carb just to get it running. Once it's running I need to keep the choke partially on, or else it will die. And when I try to give it some gas quickly it will just stumble and almost die, but if I slowly press on the gas pedal it will accelerate, but backfires out the carb and exhaust. And there is a constant popping coming from the exhaust regardless of the rpm. I have the timing set at TDC like my chiltons manual specifies, and I just completely disassembled the old Rochester and made sure ever passage was clean and insured the float level is correct, the accelerator pump leather seal is also in good condition and makes a nice seal. Plug wires are all in the correct orientation for the 153624 firing order. The exhaust also seems to be building up carbon on the tips pretty quickly as well as the spark plugs getting very black. This is kind of stumping me, and ideas of what to take a look at next? Thanks.
Nik

Have you done a valve adjustment? Or done a compression test?

Check for bent pushrods. If it pops all the time the timing is off or bent Pushrod.

Valves are within spec and all cylinders have even compression.

Already had the pushrods out and they are straight as an arrow, I'm thinking its a problem with the timing, but I set the timing to TDC just like my chiltons manual specifies so I'm not sure what the issue is.

Make sure the distributor is inserted correctly (pointing to #1 when the piston is TDC on the compression stroke) and all the plug wires are on the right terminals on the distributor cap.

Yes sir, distributor is inserted correctly and all the wires are in order.

After rereading your original post, this seems to be a fuel problem, not an ignition problem. The popping could be caused by excess fuel sitting in the intake manifold where the hot gases from the intake valves is igniting it, or the valves themselves due to carbon buildup. The plugs getting black is a sign of excess fuel in the cylinders, which supports that diagnosis. After driving it a little, return to the garage. Remove the carb and look into the manifold with a flashlight. If the manifold is wet at all, that's a confirmation that too much fuel is getting in to the manifold.

However, you also state that you have to choke the carb to keep the engine running. That is counterintuitive to the other symptoms you describe. Choking indicates fuel starvation. So it appears you may have at least two problems. You can only solve one problem at a time.

If it were my truck, the first thing I would do is tear the carb down again and go over the rebuild step by step, making sure every setting is precisely correct, every valve is free, functioning correctly and not burred or nicked or sticking for some reason. As you're rebuilding it, make sure that the float is free to move through its entire range of motion and not hanging up on anything. Sometimes a gasket can overhang enough to cause problems with float movement. Make sure the float valve is able to move freely as well, doesn't stick open or closed and seals properly.

check for vacuum leak at intake manifold to head. all your symptoms point to a vacuum leak

One way to easily check for a vacuum leak is to (with the engine running/idling) very slightly open an unlit propane torch and place the opening all around the carburetor, around its base, and around all mating surfaces of the intake manifold. When/if the idle changes, you have found a leak.