fossil
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Is it a detent ball and spring?
Hi Tim.Here's a pic of an HDC44 carb with what appears to be a vent with a screen over it. It doesn't seem to go anywhere as it directly in the path of the throttle rod and doesn't pass air either way.
I've seen it on other carbs and was wondering if anyone knows what it's for?
View attachment 278616
Hi Tim.
That HDC looks like the version that had the accelerator circuit integrated into the idle transition ports. I have run into a few. It applies impulse into the idle circuit upon transition of the index in the throttle shaft. I suppose it was there to allow the L to be set rather lean and still have enough fuel to elimate bogging when transitioning through to WOT. Here is a link to a diagram/post I tried to make on Another Site. I find them rather finicky to get running correctly. But, I see you also mention it vents directly into the Venturi. I have not seen one with the index in the shaft that does not lead directly to the idle circuit through the brass jet. I wonder if they eventually started blocking parts of that circuit with brass plugs and gaskets while they used up that run of carbs?
https://www.arboristsite.com/community/threads/homelite-chainsaws.101147/post-6916068