Marvel shebler carb rebuild

I just got a TE20 in and have been redoing some of the older " fixes" that have been done to it over the years. The original carb was replaced a while back with a Chinese knock off, luckily the previous owner still had the original. It ran on the Chinese knock off, idled nice but stumbled on a rev and then would die. I went to the original, cast iron carb and tore it apart and seen a fair amount of rust in the bottom of the bowl, but other than that it looked clean. I soaked it for a day in Chem dip, blew it out, wire brushed the bottom rust with a dremel and ran a wire through all the passages and reassembled it with a new kit. Installed it yesterday and it blew black smoke and appeared to be loading up badly, it would rev up but man it blew some black smoke.So I took it back off and disassembled it and it s soaking again. Next I m going to drain all the fuel, refill with fresh fuel ,install new points rotor and condenser, then do carb all over again and retry. What do suppose is the best chemical to clean the fuel tank with the baffles still in it and what do you use to clean the rust out of the bowl of the carb? I think there is rust in the passages.I m guessing he had water in his gas as the new carb had some brown powdery type of substance in the bottom of it as well. But wasn t rusted. The tank isn t terribly rusted but has some in it according to the sediment bowl. Any how sorry for the long post. .

Why are you changing ignition system
parts? Troubleshoot the fuel system.

Is it getting plenty of fuel to the bowl?

Is the float working and set?

The carb isn't missing any seats is it?

i bet the float has a hole in it and gas has entered it and now it cant close the needle and seat. from your description , the only thing
that makes sense. plus you have not told us or verified that the float is good plus set level. most important thing.

(quoted from post at 12:07:23 08/20/22) Why are you changing ignition system
parts? Troubleshoot the fuel system.

Is it getting plenty of fuel to the bowl?

Is the float working and set?

The carb isn't missing any seats is it?

Click to expand...

it s smoking black, I m sure there s more than
Enough fuel being burnt.
I simply changed points due to the fact they were pretty rough while waiting on carb to soak.
The float was the first thing I thought of, it has no holes and the setting is/was 1/4" from the body. I still think it s plugged somewhere,

When you got it running, would it black smoke and die at idle? Was there gas
dripping if it sat not running and the fuel valve open?

If so, those are symptoms of flooding, the bowl over flowing with gas. The
result of a sunk float, defective needle valve, or trash caught in the needle
valve.

If no excess dripping, and it would idle, and a big plus if the idle mixture
would adjust, then it is not flooding and the float, needle valve are ok.

All the fuel passes through the main jet. You should be able to lean it by
turning the main screw in. If it will not lean to the point that it won't run
or even idle, something is wrong with the adjustment screw that it is not
reaching the main jet.

Also compare the size of the venturi between the two carbs. The venturi is
sized to the engine displacement.

Assuming you installed a new needle and seat from the kit. Did the new needle seat screw fully into place and tighten onto the gasket properly? I have heard cases of the seats not fitting properly and the installers did not fully seat them which allowed gas to come down the threads bypassing the needle seat.

Does the needle move freely? Are the floats rubbing the sides of the bowl somewhere. Have the floats been damaged, like the sides bent in? That can reduce the buoyance as the displacement surface is reduced. Water freezing around them could do that.

If you find a hose barb fitting that will fit in the bowl drain, you can use it and a piece of clear tubing as a sight glass to see where the fuel level is actually at in the bowl.

Fill the bowl with gas while the carb is apart and see if any gas is getting from the bowl into the intake passage. That would indicate a crack or porous spot.

(quoted from post at 16:34:13 08/20/22) When you got it running, would it black smoke and die at idle? Was there gas
dripping if it sat not running and the fuel valve open?

If so, those are symptoms of flooding, the bowl over flowing with gas. The
result of a sunk float, defective needle valve, or trash caught in the needle
valve.

If no excess dripping, and it would idle, and a big plus if the idle mixture
would adjust, then it is not flooding and the float, needle valve are ok.

All the fuel passes through the main jet. You should be able to lean it by
turning the main screw in. If it will not lean to the point that it won't run
or even idle, something is wrong with the adjustment screw that it is not
reaching the main jet.

Also compare the size of the venturi between the two carbs. The venturi is
sized to the engine displacement.

Click to expand...

that s the odd thing Steve, it will run at idle just black smoke like an old steam engine only it s black smoke. There is no dripping from carb, if it sets it s doesn t leak. So I m fairly certain the float positioning is correct, I also measured it at 1/4 inch from the.
body, thats what it calls for.The kit I got is fairly generic, it says it s for a to30,to20, and fits a few others. I ll compare venturis today, I ll also do a double all the rest of the stuff. Thanks Jim and Steve and all who replied. I ll reply back with results tomorrow. The carb is still soaking..

Something else to check, some of the more complete kits come with new jets, and
mixture adjusting screws, along with a lot of other parts.

Often the parts are wrong. Be sure to compare them closely and check the
existing parts, especially if you have no history on the original carb, as in
did it work before it was removed.

(quoted from post at 19:25:58 08/23/22) Something else to check, some of the more complete kits come with new jets, and
mixture adjusting screws, along with a lot of other parts.

Often the parts are wrong. Be sure to compare them closely and check the
existing parts, especially if you have no history on the original carb, as in
did it work before it was removed.

Click to expand...

Here s an update, I got it running like a champ, the gas was kinda junky and it has rust in the tank, so I m cleaning the tank and reinstalling.