Bob Lang writes:
> Ken Streeter wrote:
> >I have received many responses regarding my TR6 which is missing
> >occasionally at speed on the highway...
> > [stuff deleted]
> >It turns out that the spindle coupling between the throttle shafts
> >of the carbs has play in one direction. What I mean is that if one
> >turns the throttle spindle for the rear carb manually, the throttle
> >spindle for the front carb moves too, with no play. However, if one
> >turns the throttle spindle for the front carb, the spindle coupling
> >in the middle slips for about 30 degrees, and then starts to turn
> >the rear carb throttle spindle...
> 30 degrees sounds a little excessive. Are the little 1/4" screws that
> secure the spring-thingies to the throttle linkage tight? Mind you, there
> is supposed to be a few degrees of throttle action before the throttle
> plates move (not sure why, but things just don't work right if this is
> not the case.)
The little 1/4" screws were all tight. The play is not in the folded
spring couplings, but in the center piece (the piece is on plate BA,
illustration 75, "Spindle Coupling Assembly" in TRF's TR6 manual.) It
seems that this piece should give about 15 degrees of travel between
the arm connecting to the throttle control rod, and the carb throttle
shafts. This 15 degrees of travel (effected by the slot on this piece)
works just fine. The problem is that the rod on this piece to the
front carb turns immediately, while the rod on this piece to the rear
carb delays about an additional 30 degrees. This appears to be due to
slippage of the little prong that grabs onto the hex nut.
> If there is no play in that part, the throttle is very "notchy". In
> otherwise it is very hard to feather the throttle. You will notice this
> as you cannot transition from no throttle to any throttle position without
> lurching the car.
Yes. With the "frozen" coupling in, I noticed (and expected) that
throttle response is immediate. (too immediate) A very light touch
(slow changes) on the gas pedal was needed, but it was still possible
to start off smoothly. I'm hoping to either fix the stuck one, or fix
the one with play...
In the meantime, I'm kind of hoping that using the stuck one makes my
at-speed misses go away, though! (I don't suppose that anybody has an
extra one of these spindle couplings that they don't need just sitting
around?)
> [stuff removed]
> >While I had the plugs out, I finally performed a compression
> >check... .
> Uh-oh. Well, if the car has a lot of miles, it could be ring time. I
> wouldn't be too concerned. But you should keep an eye on this. Of
> course you know to "open the carb dampers" when you do this compression
> test, don't you? If you don't open the dampers, you might get erroneous
> results.
Hmm. I didn't open the carb dampers. I'm not quite sure what you mean
by this. Do you mean I should have pulled out the choke? Or taken the
air valves out of the carburetor? Or simply mashed the gas pedal to
the floor when cranking the engine? Or some combination of the above?
I did notice that it generally took 3 or 4 revolutions of the engine
for the pressure gauge to reach its maximum. I wasn't sure if
this was because of the above, or because of the fact that it is
necessary, in a compression test, to not only pressurize the combustion
chamber, but also the length of hose to the compression gauge.
--ken
Kenneth B. Streeter | ARPA: streeter@sanders.com
Lockheed Sanders | UUCP: ...!uunet!sanders.com!streeter
PTP2-A001 |
65 River Road | Voice: (603) 885-9604
Hudson, NH 03051 | Fax: (603) 885-0631
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