350 smokes white on startup until warmed up a little. Put a new quadrajet power built carb on, their next build up from stock. Plugs are dry carbon fouled. Would you think the valve stem seals need replaced or the carb is to rich for the stock 350? Thoughts? Thanks.
You need to get a wideband O2 to see what the air fuel is. Sounds like it's way rich. In re reading you post, you didn't really say if the carb was responsible for the black plugs. Were they clean prior to the carb? If the plugs were clean prior, why would you suspect anything else but the carb if thats the only change?
Just had people say seals but I wasn’t buying it. Plugs were new. Got a good deal on this new carb so changed it out. Not sure what mods are done by quadrajet power to make it their next step up for performance. Maybe bigger jets, not sure. Bored .010 over stock 350 engine. I know an o2 would tell me.
that was my question as well. If they weren’t new when the carb went on start with fresh ones, drive it a bunch without excessive idling and go from there. Also check your timing.
Plugs were new. Timing is good. Pretty sure it’s just way rich. Carb may be setup with different jets and rods for a bigger cam. Just a thought. Need to figure out what stock jets/rods are supposed to be on this 72. 350 correct carb.
Other then at close to full throttle having the correct primary jets and metering rods means ZIPPO if the new carb was built up with too stiff a power piston spring, or if the piston itself is hanging up, or if for mechanical reasons your motor is not pulling the level of idle vacuum that it should. If you have a vacuum gauge I would hook it up and note what your vacuum is at idle, then I would swap in your spring from your old carb and see if things change a lot for the better.
A little white smoke at startup is normal in the wintertime, it's just water vapor. Black smoke would mean the carb is too rich. If your choke isn't opening properly during warmup, that'll foul plugs too. Did you adjust the idle mixture screws? Watch your choke, and as Steve said, check your vacuum.
Put a small screwdriver into the vent with the engine running. Make sure the power piston is being held down by engine vacuum.
Thanks all. I will check all these when I get home today. It’s white smoke at idle until it warms up no matter the weather. Was doing it in summer also. Choke seems to be working properly.
White smoke is just water burning off in the mufflers. Condensation is a byproduct of combustion That's why mufflers rot out. You have to get the exhaust hot enough to burn all that away
Water condenses in the hot exhaust system as it cools down. Then when you start the engine cold, water vapor will be expelled from the exhaust until it comes up to temperature.
It’s a little more than the normal condensation. I will be checking everything mentioned above later today.
So had a undetected intake manifold leak. Fixed that. Adjusted idle mixture screws. Cleaned plugs. Now has 14 vacuum at idle. No more white smoke at start just the wispy condensation untill it warms up and burns off the condensation. Thanks.
