a crude device

[sean sherry]

I've been through all the previous detailed posts about Aux Air Valves and as detailed and informative as they are, I can't help thinking that maybe too much is expected of them. (Wax Bulb types ) Particularly when dealing with rather old cars. They are rather crude mechanical devices long past their use by date. One Post points out that they should start to close up at around the high 60% and with the common fitting of 70% thermostats, a down hill run on a cool day must result in a fast idle situation. An 80% plus thermostat would be a happier bed fellow.
As a bit of a hit and miss item I wonder if someone can tell me how much adjustment can be achieved via the Air adjustment screw. The unit I just fitted did not close off 100 % and the Air screw is around one and a half turns out. The original cleaned valve now closes off 100% , Is there enough adjustment to set the idle at around 750 RPM ?
Lastly, did the Valves close off 100% when new ? ?

 

[sean sherry]

I'm looking forward to the meeting on 9th. I'm bringing along an Air valve , a thermometer, and an open mind. I've been reading some threads from the USA on testing these valves . To test , just stick them in the fridge for a while to see that they open ok, then into some boiling water to watch them close fully. i.e., passing no air. They were referring to all K Jetronic systems fitted to numerous makes and models. Not especially Mercs. I tend to agree with this . I now know that the valves are supposed to close fully and that there is enough leeway in the idle air screw to set the hot RPM. The S/H valve I bought for my car, and cleaned up ,did not close fully but it works just fine ,. My cleaned up original valve closes fully on test and I'm sure it to will be ok when fitted . As I see it now as long as the valve opens when cold and closes when hot, not to worry about any precise temperature response............... A crude device indeed. Sean