The Stovebolt Site Forums The Shop Area Engine Shop Running Rich

49 Chevy panel truck model 3100 with a rebuilt 216 engine. Attempting to set the engine up, but it seems to be running to rich. There is little or not smoke but the exhaust is so rich that you can't stay
in the garage with the door open, my eyes burn and the exhaust makes it hard to breath. How do I lean it out so that it's not so rich and to get the engine to idle smooth. Thanks for the help.

Regards,

Dave

There is something wrong with your carb. If it is a model B Rochester they are easy to work on. First make sure the mounting gasket has a cutout to alow vacuum from the manifold to reach the hole in the bottom of the carb. If gas is running down the throut of the carb when you shut it off, then you have dirt in the needle & seat or the float is bad. There has been a lot of posts on this subject. You might find a lot of info doing a search.

Thanks for the insight, the carb is a W1, that is typical for the 49 216 engine. The carb was rebuilt but I am of the opinion that there is soemthing wrong with it still. How does one lean it out to make it burn less rich. Thanks


Regards,

Dave

You can turn the idle mixture screw in but I dought if it will do much good. You are going to have to go into the carb & find out what is wrong. It could be a float full of gas or the level is not set right. The metering rod or link may not be going down into the jet.

As to the idle mixture, your right I adjustred it and it did little or nothing. Will changing the octane setting on the vacum advance affect it. Thanks

Regards,

Dave

Seems to me that running rich is running rich, not timing. I guess maybe poor timing wouldn't combust the gas/air charge properly, but that doesn't seem likely . . .

When we were reassembling our freshly-rebuilt 216, we also freshly rebuilt our Carter W-1. Along with some other kinks, we had a rich situation, with quickly fouling plugs, and dribbling gas after shut-off.

Turns out the float valve seat had worked loose (we probably hadn't tightened it properly), so gas would keep flowing, even with the float up. Easy fix.

Possible leaking float, as well. I know disassembling the carb can be a pain in the A$$, but take it slow, don't lose any parts, and check the float. It's not too bad to just pull the top off to get to the float. Float should basically sit level when the assembly is held level. There's a proper measurement, can't remember it right now. Double check the float valve and pin, and seat. If they're all good, and float is reasonably close, you should not get a drastically rich condition.

Report back what you find. Hope this helps!

-Michael

Advanced timing will increase tailpipe hydrocarbons (unburned fuel) significantly, especially on a cold engine. Timing set around TDC will usually produce the fewest hydrocarbons, but the engine will run sluggish and possibly hot. In the earlier days of emissions testing, retarding the timing was an easy trick to clean up a car failing for high hydrocarbons. Retarding the timing could reduce the tailpipe hydrocarbons by 1/2 to 2/3rds. Manufacturers have been retarding timing on cold starts for years to clean up the tailpipe.

John