ok after someone suggested i will repost this here. what i have is a 51 8ba motor with 8ba carb. i have had the carb rebuilt because of this leak and it is still leaking. it is leaking from where the linkage goes into the throttle body. i replaced the original throttle body and it leaked again. it seems to only leak after i park it. takes about 2-3min to start leakin. it only leaks from where the linkage goes into the throttle body. any help would be appreciated. as i have been back and forth with this for 2 mos. and its drivin me nuts.
Are you using stock mechanical fuel pump. Is it new . These carbs are notorius for seeping after engine stops running. They dont like a lot of fuel pressure . Check the float level maybe its a little high in the bowl. A lot of guys run electric fuel pumps with a pressure regulator and a manual switch to the pump. Kill the pump a while before you shut the engine off to drain the fuel bowl. Ive got the same problem with the two carbs on my 49 . If it sits after running a while and you try and restart all that fuel seeps into the cylinders and it runs way rich for a while.. Good luck.
i have a brand new mechanical fuel pump (2 weeks old) and no pressure regulator. just seems to leak after shut down.
Sounds like your shaft hole at the throttle body is worn and in need of shimming. Go to the tech section. 286merc has a very informative essay on rebuilding the old carbs. http://www.jalopyjournal.com/forum/showthread.php?t=4618
i have replaced the throttle body with one that supposedly had that done. maybe it hadnt. the throttle body was from a reputable person in CT. i have had people tell me it might be a vaccum leak ? or maybe fuel boiling after i turn off my car. it runs 180-190 in 110 heat here in vegas. im starting to wonder if i should replace the whole carb. but im leary about spending 250-350 bucks for a 8ba carb that might keep doing this. my main concern is fire. i dont want the car to catch fire.
Measure float level. It should be the LOWEST specified setting or even less. That is going to be the BIGGER of the numbers given, since you are measuring distance from the top. Too high a level can allow syphoning or perking over as components hot soak at shutdown. Allied causes--blocked air bleed holes in nozzle bars, missing/dirty check ball and needle in acc pump circuit, bad gaskets on nozzle bar mounts. Get a good exploded picture and carefully takeitapart yourself--just keep careful track of what came from where, looking for dirt, loose or broken gaskets, etc. This is a simple device, requires no special tools, and is a real good place to start learning carbs--I would never trust a carb done by some unknown expert! It's a simple carb and doubtless has a simple problem, and the HAMB is certainly able to get you through the learning pracess, as long as you don't let that check ball roll under the bench...
Is there a hole in the upper part of the fuel bowl . If there isn't drill one to ventilate the bowl. JMHO.
The "paper" type power valve gaskets are actually two pieces glued together and will leak fuel from the vacuum port and it will come out around the shafts. Learned this a long time ago and use the nylon gaskets that do not leak. FYI, you do not need to "vent" the bowl if it has a venturi tube (only on certain 91-99 carbs need to be drilled) Fuel pump pressure after shut down??????????
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