Any solution for lumpy idle?

[s class]

Its also worth sticking a CO meter up the exhaust pipe, and setting the idle mixture properly.  I've found that an incorrect idle mixture causes a significant deterioration in idle quality. 

Next, it may be worth checking the condition of the engine mounts and dampers. 

[hans moleman]

If I had access to a CO meter I would love to know how she is running, but I don't so I just started fiddling with the CO screw on the fuel distributor. CW adjustment yielded a massive increase in idle speed before bogging down again, some careful back and forth and I seem to have it dialed in pretty good, idle has smoothed out some. Since no adjustment should ever be necessary I figured something was screwy. Well a spray of carb cleaner all around the intake exposed a small vacuum leak at the very rear of the intake on both sides, sucks because the intake gaskets are all new and dressed with hylomar, bolts are quite tight too

[koan]

If I had access to a CO meter I would love to know how she is running, but I don't so I just started fiddling with the CO screw on the fuel distributor. CW adjustment yielded a massive increase in idle speed before bogging down again, some careful back and forth and I seem to have it dialed in pretty good, idle has smoothed out some.

I do it much the same way and I've checked with an AFR meter, it's pretty close.

Slight movement of the air flow sensor flap, a millimeter or less will richen the mixture.

If the mixture is lean the flap movement will increase RPM, if mixture already rich RPMs will drop, I aim for the spot where RPMS no longer increase.

koan

[calvin streeting]

Slight movement of the air flow sensor flap, a millimeter or less will richen the mixture.

If the mixture is lean the flap movement will increase RPM, if mixture already rich RPMs will drop, I aim for the spot where RPMS no longer increase.

koan

thats a really intresting way to set a kjet..

cool.

[jbrasile]

koan, great tip.... didn't know that trick...

tks

Joe

[koan]

koan, great tip.... didn't know that trick...

Comes from tuning old English cars with SU carbs that had a lifting pin that richened up the mixture much the same as pushing down on the plate. These cars had engines about the same capacity as 1 6.9 cylinder!

Don't know if my tip will get you through US emission tests...

koan

[hans moleman]

Emissions tests are a thing of the past for older vehicles here in Connecticut . Took the car out last night and marveled at how smooth and quiet the engine was at idle. I'm not sure what happened to the mixture screw to begin with but it was set really lean before adjusting.