Thanks, everyone. I'll pull the top of the carb off this weekend and try adjusting the floats. Broncnaz, what do you suggest I cover the fuel line with? My line is rubber coming up from the fuel pump. I don't know if that makes the heat problem worse or better on the fuel line. I think the shielding is a good idea, but I'm not sure what to use.
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Carb problem
- Thread starter valveamp
- Start date
Rustytruck
Bronco Guru
- Joined
- Feb 24, 2002
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Google fuel line insulation.
I've never had a problem with an over heated fuel line raising the fuel level after the engine is shut down. Of coarse it only gets over 115 here in Tucson occasionally. Your float settings are way too high and you have no reason to believe there is any thing more to address. The dry float setting instructions in boogie's video by Mike's will get you half way there. The wet float setting completes the job. The wet setting is simply the fuel level setting. Holley wouldn't put a sight plug on their float bowls if the dry setting was all that's needed. Once the fuel level is set and the engine is turned off , monitor the the level for 15 min. If the level goes up you may have fuel boiling in the fuel line. If it holds steady, a hot fuel line isn't part of the problem. Read this thread from Ed's Carburetor Forum;http://www.network54.com/Forum/88781/thread/1260281683/Autolite+4100+1.08+new+issue, which is an excellent source of information on 2100-4100 carbs.
Jckkys, Thanks for that link. It was very helpful for me to better understand what you guys are talking about and "wet setting" the floats. From my one observation, I would agree that the fuel level is way too high. I guess I never thought you could run the engine with the top of the carb off.
Cautiously Optomistic
Hello...Here's an update on my situation. Yesterday I removed the top of the Autolite 4100 carb and started the engine. A little bit to my surprise, it ran fine. I guess I was just expecting a problem with the top off, but there were no problems. After the engine warmed up a little and the fuel in the bowls had a chance to equalize, I measured the level of the fuel from the top of the carb. Sure enough, both bowls were significantly higher than the "spec". I did notice that there is a little "channel" that runs between the two bowls on the driver side, but this channel only goes down so far in the bowl. As I first encountered the carb, the level was above the channel, so that if one bowl had a problem, the excess gas would move over to the other bowl. Anyway, I started with the primary bowl and adjusted the float by bending. This took several iterations, but I was able to get the fuel level at the spec. I noticed that at the correct level, the fuel was below the connecting channel level, which I thought was probably good. I then moved on to the secondary bowl and did the same thing. After multiple bend and measures, I got the secondary bowl to the correct fuel level. After putting the top back on the carb, I took it for a drive up the freeway, which was just as long or longer than I did when I was having problems. Upon returning home, I checked and there was not fuel coming out of the vent holes on top. I let the carb set for a while and checked again, still no fuel coming out. I then started the engine and it fired right up, and no fuel coming out of the carb. I have driven it 2 more times on short trips with no issues. So, I am now cautiously optimistic that I have solved the problem. I've thought that before and been surprised when the problem returned, so I'm not declaring victory yet. I need more freeway driving time. In the mean time, last week I ordered a thermal blanket to wrap around the fuel line, some gold reflective, metallic tape to put on the under side of the float bowls, and a 1/4" insulative spacer from "Carb Cool". I intend to install these when the come in just to help with the thermal problems. In the mean time, I'm keeping my fingers crossed that I've solved the problem.
As a side note, my previous carb was a Holley Truck Avenger. I was never happy with that carb as it would frequently stumble upon acceleration. Even tuning it on a dyno did not solve that problem. I'm happy to report that the Autolite 4100 runs much better than the Holley ever did. No stumbling, not even when it was hot.
Thanks for all of the help.
Hello...Here's an update on my situation. Yesterday I removed the top of the Autolite 4100 carb and started the engine. A little bit to my surprise, it ran fine. I guess I was just expecting a problem with the top off, but there were no problems. After the engine warmed up a little and the fuel in the bowls had a chance to equalize, I measured the level of the fuel from the top of the carb. Sure enough, both bowls were significantly higher than the "spec". I did notice that there is a little "channel" that runs between the two bowls on the driver side, but this channel only goes down so far in the bowl. As I first encountered the carb, the level was above the channel, so that if one bowl had a problem, the excess gas would move over to the other bowl. Anyway, I started with the primary bowl and adjusted the float by bending. This took several iterations, but I was able to get the fuel level at the spec. I noticed that at the correct level, the fuel was below the connecting channel level, which I thought was probably good. I then moved on to the secondary bowl and did the same thing. After multiple bend and measures, I got the secondary bowl to the correct fuel level. After putting the top back on the carb, I took it for a drive up the freeway, which was just as long or longer than I did when I was having problems. Upon returning home, I checked and there was not fuel coming out of the vent holes on top. I let the carb set for a while and checked again, still no fuel coming out. I then started the engine and it fired right up, and no fuel coming out of the carb. I have driven it 2 more times on short trips with no issues. So, I am now cautiously optimistic that I have solved the problem. I've thought that before and been surprised when the problem returned, so I'm not declaring victory yet. I need more freeway driving time. In the mean time, last week I ordered a thermal blanket to wrap around the fuel line, some gold reflective, metallic tape to put on the under side of the float bowls, and a 1/4" insulative spacer from "Carb Cool". I intend to install these when the come in just to help with the thermal problems. In the mean time, I'm keeping my fingers crossed that I've solved the problem.
As a side note, my previous carb was a Holley Truck Avenger. I was never happy with that carb as it would frequently stumble upon acceleration. Even tuning it on a dyno did not solve that problem. I'm happy to report that the Autolite 4100 runs much better than the Holley ever did. No stumbling, not even when it was hot.
Thanks for all of the help.
