In a message dated 97-10-14 10:37:52 EDT, Chris_Lillja@Pupress.Princeton.Edu
writes:
<< I spent the 2nd half of the weekend going nuts on a set of freshly
rebuilt HS6's. They're quite beautiful, clean, polished and they
adjust to a beautiful, steady 900 rpm idle....
Once prodded, however, they don't seem to want to return to idle. >>
I've seen this idle problem on lots of TR3's, including one of my own. I
believe it is caused by worn throttle shafts or worn throttle shaft holes in
the carb body. Did the rebuild include a new set of throttle shafts and
bushings? (or oversized throttle shafts in bored holes?) I have found that
slop in the fit between the shaft and the carb body, in addition to causing
an air leak, and making the carbs hard to adjust properly (at least in
extreme cases) will cause the symptoms you describe. The throttle shaft has
side loading, all applied at the front of the front carb, from the
accellerator return spring, and if the throttle shaft hole is oversized, it
wont turn on its axis, but rather will "wallow" in the hole. (obviously I
have absolutely no command of engineering terms, but I hope you get what I
mean.) This will keep the throttle plate from closing right. I have found
that if I "Goose" the accellerator, (another great engineering term) the
idle will return to a lower idle than if I ease off the throttle. I'm
thinking it might help to switch the carb bodies, front to rear, since the
front of the front carb probably takes most of this side load. Also, Bob
Schaller's book (More BS About TR's) contains plans to add a throttle return
spring between the two carbs, which should, logically, help keep things
straight, and even out the wear. Hope this helps.
Paul Vander Woude
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