Engine rebuilt and smoking badly.

[Megoto]

Hey people, ho's it going? I finished rebuilding the engine in one of my 154's and got it fired up today. The problem is she is dumping black smoke out at all throttle ranges. Set the timing with timing light, tried adjusting mixture on Carburetor, has new air filter and lines and passages have been cleaned. I cannot figure it out. Only problem I'm having is my needle valve in my carb keeps sticking open allowing fuel to pour out when tractor is isn't running. Any ideas?

[Eugene]

The problem is she is dumping black smoke out at all throttle ranges. Only problem I'm having is my needle valve in my carb keeps sticking open allowing fuel to pour out when tractor is isn't running.

Excess fuel.
Carburetor float not set correctly and/or needle valve stuck open.

[tst]

do not keep running it, the fuel will wash down your cylinders walls and possibly damage them or pistons, fix your carb

[feg7846]

Black smoke - Carb problem. Sounds like float sticking. Don't know if you rebuilt the carb, or maybe replaced the carb, but the new needle valves that they are putting in the carb, do not have metal tip. Some kind of composite material that is subject to sticking. Just rebuilt my carb on my 47 cub and installed the new needle valve. Had to take carb apart and use my old needle valve because new one was sticking. Just saying............

[Megoto]

Thanks for the quick reply folks I will look at the carb again tomorrow and yes I did rebuild it and yes the new needle has that composite tip.

[Megoto]

Ok so I replaced the Needle and seat with a known good one from an older carburetor I have for back up. Still have the same problem. So put the parts back in the back up carb and put that on. Same problem. So I took the carb off of my running 154 and put that on. Same problem so I'm not sure it is a carb issue. I'm guessing I did something wrong somewhere but all cylinders are testing at 118-121 psi on the compression test. I'm stumped

[Bob McCarty]

Did you adjust the float height and drop?

[Megoto]

Not on the one I took off the running tractor that doesn't have any issues.

[Jim Becker]

Recheck the firing order on your spark plug cables.

[Megoto]

Well I took a short video of what it is doing but I can't seem to add it. I rechecked firing order from distributor and it is correct.

[tst]

its black smoke or blue ?

[tst]

what color are the plugs when you pull them

[Megoto]

The plugs are now black. And the smoke looks black to me

[Eugene]

Miss firing on one or two cylinders will cause dark exhaust. Two plug wires on worn cylinders? Cross firing/miss firing inside distributor cap?

Check the air cleaner. Plugged up?

Ignition timing? Engine to ignition timing?

Pause, take a break. Start 100% engine tune up all over again.

[Megoto]

Man I just rebuilt this engine. That would suck but I'm stumped so I will look at everything again