Pete & Aprille Chadwell wrote:
>
> Greg Hutmacher wrote:
> > The car is now running as well as it ever has, but there is one more
> >mystery. In the book, it tells you to, with the engine warmed and running,
> >remove the air cleaner and lift and hold each carb piston about a 1/4 inch
> >with a screwdriver as a test of fuel/air mixture. If you are too lean, the
> >car's idle will drop drastically and it will try to die. If you are too
> >rich, the car's idle speed will increase. And if it is correct, I think it
> >said the car's idle will momentarily increase and then return to normal.
> >Using this test, I found my car was trying to stall when I lifted the carb
> >piston. I adjusted the mixture needle all the way up into the piston to its
> >stop at full rich position but the "lift the piston 1/4 inch" test still
> >caused the idle to drop and falter. Why? What am I doing wrong? It did this
> >on both carbs. Anyway, it doesn't really matter, I adjusted the needles to a
> >point where the car is running very well regardless so I think I'll leave it
> >alone. Thanks again to everyone for their help! Regards, Greg Hutmacher
>
> Then Ed Woods wrote:
> >Don't know what book you're using, but the one's I've read suggest
> >moving the piston up only 1/32". I'd expect the engine to stall if I
> >lifted the piston 1/4".
>
> First of all, I should point out that this isn't the first I've heard that
> the 1/4 inch lift is way too much. I've had guys tell me this before.
> Secondly, damned if it isn't starting to look like they're right...
> according to the 1/4 inch lift test, I have NEVER been able to get a rich
> enough mixture. Greg seems to have had the same experience using this test.
>
> I guess the question is, why is it wrong in the Bentley manual? And if it
> IS wrong in the Bentley manual, then why the HELL does anyone use the
> manual at all? The Bentley manual OUGHT to be the final authority for this
> kind of stuff, save for a typo here and there. Are we saying that the
> Triumph engineers didn't know what they were talking about?
>
> Ed, I'm not meaning to "challenge" you here... I already said it looks like
> you're right and that others have told me the same thing, but since it's
> the Bentley manual that recommends 1/4 inch, I'd like to know what source
> YOU have that says 1/32? Because I've only heard that through the
> grapevine, so to speak... I've NEVER seen it in print anywhere.
>
> I'm not your average male... I usually read directions, and follow them
> closely, particularly when I don't know anything about what I'm doing.
> That's how you learn... you assume FIRST that you DON'T know the answers
> (even when you think you do) and then you read or experiment or whatever.
>
> I'm not trying to challenge or offend anyone... just looking for the
> objective answer. Where is it written that the piston ought to be lifted
> only 1/32 of an inch, and why does the Bentley manual suggest 1/4 inch?
>
> Pete Chadwell
> 1973 TR6
Frankly, this is an issue I've just never worried about.
I twist a screwdriver of the proper width under the
piston until it moves perceptibly. If the mixture is off, the rpm's
immediately move with it. I can then set the mixture dead on, on both
my cars.
I know this sounds smug, but it works for me.
--
Martin Secrest
72 TR6
73 GT6
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