Any idea what could cause white mist to come out of the carb at idle? I'm running a 283 sbc with an Edelbrock carb 500cfm. This is the first time I've seen it happen, and occurred after I had done a series of short test drives around the neighborhood. I first noticed it coming through the air filter on the passenger side. I took it off to see what was going on, and noticed that it's only coming up through that side only.....as far as I can tell. I couldn't discern a smell to it, and it's not a lot....just wispy. If I up the throttle, it stops. I did play with the air/fuel mixture prior to these test drives, but I have run the engine since then, but only sitting still in the driveway and not under load. My three thoughts are: -fuel float set too high or something to do with the fuel mixture being too rich, atomized mixture coming back up through the carb -valve lash is off (which is odd because it runs well and I just set them and double checked) which could mean the valve timing is not right, allowing exhaust to creep back up -water leaking into the cylinders. I have noticed that the driver's side exhaust pushes out tiny water droplets when running, but they don't smell like coolant or have any color. The passenger side (where the smoke is coming from the carb) has no water coming from the exhaust pipe. The head gaskets are new, and I didn't notice any cracks on them when they were removed. If it is leaking, possibly a warped head? I'm obviously hoping it's not that catastrophic, though. The car runs fine, even with the misting and water droplets spitting out of the back Ideas, thoughts?
Try running the crap out of it for about 100 mi. Then check the exhaust, probably dry right up. Lippy
Look down the carb at idle if you see any fuel coming out of the nozzles it's either flooding or running too lean.
If anything is coming upward out of the carb while it is running means cylinder pressure is coming back up into intake and through carb more than likely. Even if it were slightly flooding while running the engine vaccum would still draw vapor into engine. Pressure is possibly leaking past a valve either from too tight valve lash, leaking intake valve or incorrect valve timing. Being that if valve timing had changed via a jumped chain it more than likely would not run at all, that leaves too tight lash or leaking intake valve. Recheck lash on that side, if it showed up after adjusting lash I would think one may be too tight unless it is just coincidence that a valve began leaking right after adjusting valves. If lash is still Ok then run compression test on that side, leaking intake valve will show right up. If exhaust valve is to tight pressure would usually leak into exhaust system not into intake.
I think I figured out where it was coming from *hopefully*. I never knew what to do with the draft tube nozzle at the back of the block, so I capped it off. I tried hooking it directly to the PCV valve on the front of the carb, but it floods the engine with too much air and kills the whole thing. Somehow it blew off the cap I had on there, and I believe that the carb was pulling the smoke into the back of the air cleaner, but the vacuum wasn't enough to pull it all back into the engine at idle, so it was escaping back out on the side of the aircleaner....giving the smoke a "detour" so to speak. I'm trying to figure out what to do with that draft tube at the moment Don't want to continually replug it when this happens again and again....but don't know where to route it.
Also is the vapor coming directly up out of carb venturi or from air cleaner housing itself? Early 283's (and maybe all, I can't remember)had a draft tube for crankcase ventilation at back of engine. If this has been closed off via a freeze plug and some other ventilation system created tied into air cleaner that would cause some vapor around air cleaner,
You answered my question while I was asking it. Couldn't you get the draft tube and hose assembly and put back on it or are you just trying to avoid the slight leakage from draft vapors.
Seeing this is my first build, I went by some faulty advice (obviously) that it could be capped. I didn't even know where to run the tube I don't even know what it looked like stock, as it came with a C4B intake and no carb, no hoses, almost stripped. I did a topic search on the HAMB just now and found where someone just put an inline PCV valve between the draft tube nozzle and the PCV intake on the carb and it worked....hopefully that'll work for me.
sounds like water vapor.what year 283???stock exhaust or headers??? how long has the gas been in the tank???try a bottle of dry gas.
Problem solved, putting that inline PCV valve between the draft nozzle and the PCV inlet on the carb solved everything! Thanks for all the input!!
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