Date: Wed, 29 Nov 2000 18:08:03 -0500
From: "Martin A. Secrest" <msecrest@erols.com>
To: "Riggs, R Kevin" <rkriggs@ugsolutions.com>
Subject: Re: TR6 Suddenly Runs Rich
References: <CD08E3B5CC13D31189F90800365DDA03D61C86@hsvntx.ug.eds.com>
Kevin:
Thanks for a very thorough write-up. I'm posting this reply to the list so
others can enjoy this veritably on-topic discussion.
I've taken apart float bowls before, never particularly to my enjoyment. And
you're right -- Grose Jets are unreliable mechanisms. I tried a pair on my GT6,
and after lots of misery with them, went back to the original needle valves.
--
Martin Secrest
TR6, GT6
"Riggs, R Kevin" wrote:
> Martin,
>
> I think the problem is most likely the fuel shut-off valve that screws into
> the carb body within the float-bowl chamber. I believe most rebuild kits
> these days come with a "gross valve", though I've heard many people express
> their preference for the old, original style valves that came in the
> carburetors.
>
> When the fuel pump sends fuel to the carb, it gets dumped into the float
> bowl. A plastic float pivots on a stainless steel arm in this pool of gas,
> and the pivot arm raises and lowers a stem extending from the float valve.
> When the fuel level is high enough, the valve closes entirely, shutting off
> the flow of fuel to the carb. When enough has been siphoned through the
> carburettor, the float drops down, opening the valve again.
>
> The typical problem is that crud is pumped into the float bowl and finds its
> way into the float valve, preventing it from closing. From then on, you
> have a steady stream of gas into the float bowl, where it eventually bubbles
> up into the carb, spoiling your mixture.
>
> The short term fix for the problem is a few whacks on the float bowl with a
> block of wood. If you're lucky, this will dislodge the crud in the float
> valve. For a while...
>
> The longer term fix involves several steps. The most critical step is to
> stop the crud flowing into the carbs. The minimum fix is to put a good
> quality filter as close to the carbs as you can get it, and replacing this
> filter often. You might also consider replacing rubber and possibly steel
> fuel lines (use your judgement on what might be in poor condition), and
> conceivably cleaning and/or sealing your fuel tank.
>
> Some people have told me that they've cleaned the float bowls with the carbs
> on the car. I can't get my fingers in there to do that, so I've always
> pulled the carbs off the car to get underneath them and remove the float
> bowls. Odds are you can continue to use the existing valve, though you'll
> certainly want to unscrew it from the carb body and clean it thoroughly.
> None of this should have any effect on the rest of your carb adjustments.
> However, you'll probably want to replace the float-bowl gasket at a minimum,
> and you might want to replace the crushable brass washer that seals the
> float valve to the carb body. Consider replacing the valve itself, though I
> don't consider this a wear item.
>
> If you recently replaced your mechanical fuel pump with an electric fuel
> pump, that could also cause essentially the same problem simply by supplying
> more fuel pressure to the carb than the float valve can handle. This is the
> problem I suffered for years before finally identifying it and adding a
> pressure regulator between the pump and carbs. I'm also trying to deal with
> dirt in the fuel line, though, because my car sat unused for several years.
> In addition to varnish in the lines and carbs themselves, I think I may have
> corrosion from the tank.
>
> Hope this helps,
> Kevin Riggs
> '72 TR6
>
> > -----Original Message-----
> > From: Martin A. Secrest [SMTP:msecrest@erols.com]
> > Sent: Wednesday, November 29, 2000 3:52 PM
> > To: triumphs@autox.team.net
> > Subject: TR6 Suddenly Runs Rich
> >
> >
> > All:
> >
> > The thing about owning two Triumphs is that it's like having a pair of
> > Pugs -- pay attention to one, and the other gets jealous. My GT6 throws
> > a u-joint, and now ...
> >
> > My '72 TR6 suddenly runs so rich, the plugs foul in short order
> > (showing the black sooty plug evidence after a few hours running time).
> > Lots of white smoke, too. Any ideas as to what would cause this? I set
> > the mixture a couple months ago to spot-on, the K&N air filters weren't
> > dirty (but I'm cleaning them anyway), and the carburetors were
> > professionally rebuilt a couple years ago by the PO.
> >
> > The choke setting seems normal too, at first glance. Hmm.
> >
> > I haven't gotten into the mixture settings yet, but those don't just up
> > and change themselves (unlike women).
> >
> > --
> > Martin Secrest
> > 72 TR6
> > 73 GT6
> >
> > PS: Just a little auto/gender humor ...
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