Help Appreciated - 800/850 Carb problem?

I have an 800/850 that I bought about a year ago. It has run excellently for about a year, and now over the past month it stalls, backfires and now will not even start except after a long period of turnover. When I do get it started, it will run for about 30 seconds at low idle and then die. If I try to give it gas after it does start at idle, it dies. It acts as if it is not getting any gas or the timing is way off.

I have been working with these early Ford tractors for 20 years so I know a few things about them. I have great spark to the plugs, I put new points, coil and ignition key when I bought it, the gaps for the plugs and points are set correctly, the timing was set at 5 deg. BTDC, the gas tank is full and the shutoff valve is open and flowing. Since I have had this problem I have verified that all plugs have great spark, there is excellent compression, all plugs fire, all valves work and no valves are stuck open and I just rebuilt the TSX706 carb with a new full kit. I was very careful and did it correctly as far as I could tell.

I also static checked the timing by removing the #1 plug, turned over the engine to no. 1 at compression and made sure the engine was at 5 deg. BTDC, loosened the distributor and turned the ignition on, and then turned the distributor clockwise a few degrees until the points closed and then slowly turned the distributor back counter clockwise until the plug sparks and tightened the distributor. This is the way to do it.

Still, no start and the engine continues to act as if it is not getting gas to the piston chambers. There is plenty of proper flow to the carb and through the carb, but no gas seems to make it up to the engine. Yes, I removed the plug at the bottom of the carb and made sure that there is plenty of gas flowing into the carb. I also verified that there is no blockage from the intake manifold to the engine. When I put my hand over the carb air intake there is great suction.

Any suggestions what to look for now? I have never been so frustrated with any of the Fords that I have owned over the years.

Do I try a new carb, or a professionally rebuild carb?

Thanks for letting me vent. Frustrated beyond belief!

If you dribble a small spray of starting fluid into the inlet of carb (connection to air cleaner removed), can you keep it running with that spray?

Not really. It will start after a bit
but still die.

It acts as if no gas is getting through the carb.

Have you tried disconnecting the air filter from the carb to see if that helps? Could be starving for air, not fuel.

(quoted from post at 21:30:12 08/31/16) Not really. It will start after a bit
but still die.

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n that case, you can not argue that lack of fuel is a problem, since you are providing plenty.

blockage in bottom of carb bowl not allowing gas to jet , is my thought

Sure sounds to me like lack of fuel. Do you get enough to make the plugs wet after a little cranking? If it doesn't fire up in ten seconds you should have wet plugs and gs running out of the carb intake. I would go look at whatever I "fixed" on it last

Just for kicks, check to see that the distributor spark advance assembly is the right one.. The side mount 8N distributor turns ccw were as the NAA 6/900s turn cw and they will interchange, and not knowing total past history of the tractor!!! Your description of the problem brought this to my mind. Took several days to find it the first time and this actually happened "Twice"

The engine ran perfect for a year or so since I bought it. The plugs do not get wet at all, even after cranking the engine for a long time. It sounds like lack of fuel to the chambers. It must be a problem in the carb someplace. When I initially took it apart there was a lot of sediment in the bottom. I blew air through all of the holes. I thought that got all of that out when I rebuilt it.

I will take the carb apart again (for the 5th time) remove all of the jets, and run piano wire or some guitar wire that I have through all the holes to make sure that there are no blockages. I will post back later today.

Thanks to all for suggestions.

(quoted from post at 02:45:39 09/01/16) The engine ran perfect for a year or so since I bought it. The plugs do not get wet at all, even after cranking the engine for a long time. It sounds like lack of fuel to the chambers. It must be a problem in the carb someplace. When I initially took it apart there was a lot of sediment in the bottom. I blew air through all of the holes. I thought that got all of that out when I rebuilt it.

I will take the carb apart again (for the 5th time) remove all of the jets, and run piano wire or some guitar wire that I have through all the holes to make sure that there are no blockages. I will post back later today.

Thanks to all for suggestions.

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Another tool for cleaning is welder's tips cleaners they are not long enough for all passages but you have a very good assortment of sizes to match passages.

While you have it apart, note that the venturi has a top and bottom of differing size.