Eye burning exhaust

[all4rocks]

My cuda runs great. When i let my 440 cuda sit and idle it stinks. very strong exhaust smell. Is it running way rich?

[Chryco Psycho]

not nessisarily , if you can hear cam lope it is misfiring cylinders & pushing unburned fuel out the exhaust , if the plugs look clean & the engine runs worse with the mixture screw turned leaner usually inward misfiring is all that is causing the rich idle

[all4rocks]

Where are the idle mixture screws? Are they these? Cam lope normally causes misfiring?

[brads70]

Yep that's them.    I installed a fuel/air ratio gauge in my car. I found it to be a great investment for tuning the carb. No more guessing!
I have the same carb in a 850

[all4rocks]

What is the procedure for adjusting those idle screws? Where do I get one of those A/F gauges?

[brads70]

What is the procedure for adjusting those idle screws? Where do I get one of those A/F gauges?

If you have a vacuum gauge screw it out till you get the highest reading.
Autometer is what I have?
 

[cudabob496]

How To Adjust The Idle Mixture Screws On Holley Carburetors

[all4rocks]

Do all of the idle screws have to be turned out exactly the same? Or do you just adjust each one individually till each one reads maximum vacuum on the guage?

[cudabob496]

Do all of the idle screws have to be turned out exactly the same? Or do you just adjust each one individually till each one reads maximum vacuum on the guage?

start about 1 and 1/2 turns out, then each individually. they don't all have to be in same position.

[Chryco Psycho]

I alway try to adjust them in or out evenly so if I turn one out 1/16 of a turn I do them all & tweak once I have all of them close , you do not want one corner almost bottomed & the one on the other side 3 turns out to compensate

[all4rocks]

As I turned them in the car seems to run smoother but also got rid of all the cam lope.

[cudabob496]

As I turned them in the car seems to run smoother but also got rid of all the cam lope.

probably got rid of poor/rough idle, not cam lope.

[Chryco Psycho]

  nothing wrong with getting it to run better 

[Strawdawg]

One of the reason we get a rich smelling exhaust with cams with longer duration is the increased overlap where both valves are open at the same time for a period of time during the combustion cycle.

If one has his initial timing set relatively low (late), this increases the amount of gas that is still burning as it exits the exhaust valve into the exhaust stream.  Hence a more eye watering exhaust smell at idle.

If the initial timing is increased so that the "fire" is started earlier in the event, then less of the a/f is still burning as it enters the exhaust system which not only reduces the odor a bit but also provides a more complete burn that also creates a bit more power and improves vacuum and idle quality.   This necessitates reducing the mechanical advance in the distributor so that total timing is still in the desired range as we normally do.

[Kevin71]

Could this make a car run hot.  Or continue to run when you shut it off?