Stinky Idle

-
my5thmopar

my5thmopar

Life Long MOPAR Owner
FABO Gold Member
Joined
Jul 15, 2011
Messages
1,474
Reaction score
869
Location
Tennessee
76 440 truck engine with mild RV cam. Carb is a manual choke Edelbrock 1405. It’s running rich at idle. It is stinky with no visible black smoke. Operating is smooth at any speed and WOT. The choke is fully open and mixture screws adjusted a few times per manual. The screws will kill engine if adjusted to lean side. Might be timing but, 14 idle and about 34 all in. It really runs well and I’m thinking It’s dumping fuel. Where should I be looking. Craig
 
High float level. If idle mixture screws will kill engine, the idle circuit is working. Only other thing is secondary butterflies not completely closed. Also the needles on power circuit may be stuck. They can be checked with engine running, at idle they should pull down against spring.
 
my5thmopar said:
76 440 truck engine with mild RV cam. Carb is a manual choke Edelbrock 1405. It’s running rich at idle. It is stinky with no visible black smoke. Operating is smooth at any speed and WOT. The choke is fully open and mixture screws adjusted a few times per manual. The screws will kill engine if adjusted to lean side. Might be timing but, 14 idle and about 34 all in. It really runs well and I’m thinking It’s dumping fuel. Where should I be looking. Craig
Click to expand...
You're probably aware of this but all mixture screw adjustments should be made with the motor at operating temperature and incrementally. Not sure how far out the screws are before it kills the engine.
 
Set timing first, and investigate if you can use more initial timing. As above, set timing with engine warm. Turn screws in a bit at a time, and if you notice RPM drop, turn them back out to "peak" RPM/ manifold vacuum. End with screws "touched" a bit on the "in" (clockwise) side just enough to not affect the peak or not much.

Also determine if engine IS ACTUALLY running up to temperature, too cold a stat, missing stat, etc
 
We are working with fuel less than 30 days old i hope.
Old gas can be stinky. Cold engine makes it worse. and as mentioned, hot engine before adjustments. Timing may also play a part in this.
 
To add what others have said, what is the fuel pressure? Edelbrock/AFB/AVS are sensitive to too much fuel pressure.
 
Plug heat range can make it idle dirty. Too cold of a range.
 
if by "stinky" you mean, "makes your eyes water" while standing behind the vehicle, to me that means incomplete combustion. Could be a lot of reasons for that, but for me, it means lean misfire. Which in turn means too lean a mixture, or insufficient spark advance, or weak ignition system. OR any combination of those reasons.
 
All good suggestions. I’ve got some homework....when it warms up. Stinky=eyes burning. Should have clarified. Not lean. It’s rich. Plugs and pipes. Craig
 
You must log in or register to reply here.
-

Back
Top