gerry@speedy.att.com writes:
> I am assuming that you have the downdraft Weber. To adjust the idle
> circuit you use the mixture adjusting screw on the outside of the carb
> body. To adjust the progression circuit you have to set the float level
> properly. To do this you have to remove the top cover of the carb, and
> set the float level with the carb top held vertically. I forget the
> actual settings, but I can get them from the manual if you need. The
This brings up an interesting point -- where do you get float level
settings for aftermarket carbs? I have a 34DMTR on my X1/9, and haven't
been able to find any documentation on this carb anywhere (I don't know
of any car which came stock with one, and it's not covered in the
Haynes Weber book), though it's a fairly common carb for aftermarket
conversions. I've been setting the float level to the same setting
as the Haynes manual says the stock carb should use, but I have a
sneaking suspicion that that might be nonoptimal (and of course this
wouldn't be at all appropriate for a car which came stock with SU's ...)
> main cirrcit is adjusted by changeing the jets. Most of the driving is
> down on the progressive circuit, therefore I would check the float level,
> and then set the idle mixture. When you are adjusting the idle circuit,
Also, make sure your jets aren't clogged, and if the car's throttle
response seems strange, try another jet of a similar size. Sometimes
Weber jets (especially small ones, like idle/progression jets) can fail
in non-visible ways. A few weeks ago I had a strange problem where the
car suddenly absolutely refused to start when cold. It had a 60 idle
jet. Since I had exhausted all the logical tests for why the car wouldn't
run when cold, on a whim I decided to try changing the idle jet. I was
fairly sure that the 60 was on the small side (because the jet I'd had
in there previously was a 100), but I don't have any idle jets between
60 and 100, so just on a whim I decided to try a 55. The cold-start
problem disappeared! It still gives evidence of being too lean on the
idle circuit (backfires a little on engine braking, which usually means
a lean idle jet) but not as severely as it did with the 60 jet. I can
only conclude that that specific 60 idle jet has some sort of internal
clog (it doesn't have any externally visible clogs -- I checked).
One nice thing about Webers is that the jets are so easy to change: the
jets do clog occasionally, but it takes all of 10 seconds for me to swap
jets (with a dzus-connected foam air filter).
> make sure that the car is running on the idle circuit and not on the
> low end of the progressive circuit. I could get into details, but Weber
How do you make sure of this?
> produce an excellent book, and it really helped me to understand Weber
> carbs.
Where is this book? I haven't seen it for sale, and it sounds like
something I'd very much like to have (all I have is the Haynes).
--
...Akkana (akkana@apple.com)
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