Idle rises after warm-up

Sound like a vacuum leak or air being drawn in. Check your lines. I bet you'll find the culprit. On a side note the buzzing has not returned but it has been cool out. Once the temp outside goes up I should have more to report.

R

 

your idle set up is probably incorrect. Check fuel mixture with a gas analyzer and set bank balance with two vacuum gauges. Also follow the procedure in the service manual in setting the fuel mixture

 

the idle and mixture has to be checked and set when the car is up to full temp and the fans have cycled.

 

I disagree.. the hotter she gets the more difficult it is to set the mix... the sweet spot is as soon as the temp gauge reads over 140 when the o2 sensors would normally take over.. disconnect the sensors then set your mixture.. but I dont think Phil has a mixture problem.. sounds more like an air leak.

R

 

Any idea how I can reset the air/fuel mixture w/o vacuum gauge or gas analyzer?

I think there are two set screws (bolts actually) to do so. One bank is running richer than the other (almost like flying a twin prop plane w/both engines out of synch). I can feel the differences in pressure and gas in tailpipes.

Car has no cats/pre-cats and does have test pipes to a Tubi.

 

It sounds like you are leaning out more after full warm up.
Maybe a leaky cold start injector shuts of after all gets hot enough if it is leaking a little fuel after it should shut off.
You can not adjust your banks with out co and mercury vacuum gauges connected to both banks together.
Small adjustments in your fuel distributors make huge differences and after done with an alan wrench you have to measure your co with the screws (covering the whole to adjustment) back in since air comes through there and make a huge difference in your mixture.
Proper adjustment should be done with air by pass screws closed by the throttle screws and fuel adjustment on the fuel distributors.
Tricky to do right since your little rods effected by the throttle screws are effecting each other when you adjust one (the other changes also unless they are disconnected from each other when adjusting.
In an emergency with out tools you could theoretically adjust each side to a lean miss and then go back rich until the rpm drops but for the long run you need to be dead on on co (fuel)and vacuum both sides and your idle should fall after free revving and stop at a thousand rpm without dipping or stalling.

You can make a vacuum gauge your self out of two clear long tubes on a wood stick sucking mercury out of a container at the bottom connected to each side with little t connectors on your vacuum lines on each bank.
An accurate co meter in a shop somewhere can allow you to do this once if needed and it stays good for ever if there is no issues else where if you got a proper mercury gauge made.
K jetronic is very dependable and I adjusted mine only once in twenty years and is still perfect .
Fresh good fuel is key to keep the system trouble free

Mario

 

I'll give a go this weekend.

I did this once before and managed to get the car home okay w/o any tools or guages.

I think this will be fine to get it to the shop for proper adjustment.

Ciao,
360 Modena (on the other F-site)