carburetor issue

[edearho]

Hi gang,

Over the last year I've posted a couple times regarding a leak from my carburetor. I finally took the plunge and had the carb rebuilt (autolite 2200). The leak is gone, but now there seems to be a inproper mixture of fuel to air when I drive it. It's hard to explain, but the engine seems to be surging a bit and isn't running smoothly. My guess is that it's not getting an adequate supply of fuel. I've worked with a friend to tune the carb by adjusting the idle and the jets, but no tinkering seems to be working. Furthermore, when the engine is running the exhaust is a dirty grey color, which never was the case previously. I'm out of ideas. What can I do to tune the carb so that the engine runs smoothly again?

Any help or insight anyone could provide would be appreciated.

Warm regards.

 

[Rustytruck]

Idle mixture screws only adjust the idle Use a vacuum gauge and adjust the mixture screws for the highest steady vacuum reading. More than likely the float level is set to high or the choke is improperly set too closed. What size jets are you using. Depending on location and engine build they should be around 44 to 52. most of the time they are closer to 46 to 48. a bad power valve will make the engine run rich check and make sure its not leaking inside.

 

[Justafordguy]

X2, if the choke is opening I would check the float level and the power valve.

 

[edearho]

thanks for your input. Unfortunately, I don't know much about vacuum gauges or float levels. Does the carburetor need to be disassembled to adjust the float level?

I've been doing some more tinkering and I think I was incorrect in my assessment that the carb is getting too much air. In fact, I think it's just the opposite. The exhaust indicates to me that it's getting too much fuel and also the fact that it appears to be flooding after running for a bit. I would assume the vacuum gauge would help me assess the proper fuel to air ratio. I may need to bring in someone more knowledgeable than me to make these adjustments. But is there a quick and easy way to reduce the level of fuel being input to the carb?

 

[NYLES]

Adj the floats, they are set too high. They need to be lowered in the bowl to close the float jet sooner.

Just like adj a toilet tank just way smaller.

 

[jckkys]

Carburetors are a collection of different systems. There is a cold start enrichment system or choke, an idle system, a sudden throttle opening or accelerator pump system, a high load enrichment system or power valve, a cruise system, and an idle to cruise system or transition slot. To diagnose a carb problem, you have to isolate the conditions where your having problems to know what system needs work. You also have to know if the problem is a result of being too lean or too rich. Surging is associated with a lean condition. Black smoke is a sign of an overly rich condition. One carburetor can have both, but as a result of 2 or more systems needing adjustment. When you have surging is the engine cold or warmed up? Are you cruising, climbing a grade, accelerating, or idling? The same questions have to be answered to diagnose the smoke issue. To be sure we know what carburetor your talking about, is it a 2100 Autolite or a 2300 Holley? I know of no 2200.

 

[Broncobowsher]

Carburetors are a collection of different systems. There is a cold start enrichment system or choke, an idle system, a sudden throttle opening or accelerator pump system, a high load enrichment system or power valve, a cruise system, and an idle to cruise system or transition slot. To diagnose a carb problem, you have to isolate the conditions where your having problems to know what system needs work. You also have to know if the problem is a result of being too lean or too rich. Surging is associated with a lean condition. Black smoke is a sign of an overly rich condition. One carburetor can have both, but as a result of 2 or more systems needing adjustment. When you have surging is the engine cold or warmed up? Are you cruising, climbing a grade, accelerating, or idling? The same questions have to be answered to diagnose the smoke issue. To be sure we know what carburetor your talking about, is it a 2100 Autolite or a 2300 Holley? I know of no 2200.

^^this^^

 

[Pa PITT]

Well Vacuum gauge is supper simple . BUY one 20 bucks. & plug on .. You can't go wrong playing with it...
Then most of the advise above was very good.
.. Think back to how long it's been since you've changed your spark plugs.. I know I jumped to left field .. But sometimes Something else pokes it ugly head into the program. If for any reason the Plugs might be an issue ... Replace them with either Champions or Autolite maybe Motorcrafts NOTHING ELSE .. I SAID NOTHING ELSE......
... Nothing else since your having issues .
... I'm expecting either the power valve ... Hard for a beginner to change or the Float level after about 3 times it'll be a piece of cake.

 

[edearho]

Thanks for all your input. It's an autolite 2100. Is there a procedure for isolating the various components of the carburetor that you'd recommend? The engine surges when driving after being warmed up, but it's running tagged from the point I start it. After running it a bit or starting it several times, its probe to flood.

 

[edearho]

Hi guys,

I've spent a good deal of time tinkering with the carb, and I'm totally stumped. One issue that perplexes me is that if I turn the mixture screws (the jets) all the way down it should theoretically kill the engine, but it doesn't. Does that give anyone an idea of what could be going on here? I'm getting black smoke from the exhaust from ignition on, the engine is surging a bit and truck floods after several starts or running a bit. I know it's running rich, but any attempt to alter the mixture doesn't seem to help. Would an incorrectly adjusted float level negate the effects of working with the mixture screws?

Thanks for any input anyone might have. this is a mystery.

 

[NYLES]

First 3 posts should have been a hint!

 

[edearho]

I was under the impression that no matter how the lost level was set shutting the mixture screws all the way down would kill the engine. I will definitely look into the float level. Thanks for your input.

 

[edearho]

Float= lost. Stupid auto correct.

 

[bronconut73]

Float level homie


I can tell you are a smart guy.....your Just scared to tackle that carburetor. Once you do you will see how easy it is. The float system is just like a toilet tank.

Don't worry, you got this.
We are here for you, but look up a schematic for your carb and start studying it.

 

[NYLES]

Float controls level in the bowl and until the jet is closed fuel will not stop. Couple pics of what you need to do......When that carb was rebuilt the rebuilder set the float to some magical # on a spec sheet, IF he did that. Youll save yourself a lot of pain to adjust it.

 

[edearho]

I really really appreciate all of your continued input. One of the above posts really resonated with me in that there could be multiple issues going on here. But I will tackle the float level and go from there. Thank you again so much for all of your time and input.

 

[jckkys]

If the idle mixture adjustment screws don't kill the engine when they're turn in all the way, There has to be another place fuel is coming into the idle air. A small hole in the power valve diaphragm could explain it. Power valve are cheap and perforated ones are easy to check for. I simply suck on the diaphragm side. If air is getting through you'll know right away, just like any diaphragm. The fuel level with the engine running should be 7/8" to 9/10" below the gasket surface. Your idle has to be steady first so fuel isn't splashing out when the top cover is removed. Also do it outside with a helper to kill the engine immediately if needed.